Common RV Terminolgy and Definitions

RV terminology

For the RV neophyte, some RV terminology may seem like a foreign language! Here is a nice long list of typical RV related terms and their definitions used within the RV community.

AC or A/C:

AC is the 120 volt alternating current electrical system. (the same as ina house). AC or A/C can also mean the air conditioner.

Actual Weight:

Also referred to as “Weight” this is the measured weight of an object, such as a trailer or motorhome.

Anode Rod:

Anode rods are used in the water heater, to attract the corrosive elements in the water. These corrosive elements will corrode the anode rod instead of the metal water heater tank. The anode rod should be inspected every few months, and changed when it is corroded. The rods are used in steel water heater tanks, aluminum tanks have an inner layer of anode metal.

Arctic Package:

A feature package on an RV that adds extra insulation, double pane windows, and heat pads or strips for the holding tanks and water lines, so they won’t freeze. This is desirable if you plan on dry camping in cold weather.

Axle Ratio:

Th number of driveline revolutions required to turn the axle once. For example, with a 4.10:1 axle the driveline turns 4.1 times for each full axle revolution. The higher the number, the more torque your vehicle will have, which means more towing power.

Backup Monitor or Camera:

A camera on the back of a motorhome, with a monitor on the dashboard, so the driver can see what’s behind when backing up. It can also be used while driving, to keep an eye on your towed vehicle and see the traffic behind you.

Ball Mount:

The part of the hitch that supports the hitch ball, and connects it to the trailer coupler. Ball mounts are available in load carry and weight distributing configurations.


The storage area below the floor of the RV, accessible from the outside.

Black Water:

Wastewater flushed from the toilet, held in the black tank until you dump it at the dump station.

Black Tank:

The black tank on an RV holds the sewer water from the toilet. This should always be dumped at a dump station.


Also known as dry camping, boondocking refers to camping without any electrical plug-ins, sewer or water hookups. (While boondocking, you still have electricity from your RV batteries, and water from your freshwater tank.)

Brake Controller:

A control unit mounted inside the vehicle that allows the electric brakes on the trailer to become activated in harmony with the braking of the tow vehicle. The controller can also be used to manually activate the trailer brakes.

Break Away System:

A braking system to automatically lock the trailer brakes in case of a hitch failure, where the trailer could break away from the tow vehicle.

BTU (British Thermal Unit):

A measurement of heat referring to the amount required to raise the temperature of one pound of water one degree F. (Fahrenheit). RV air conditioners and furnaces are BTU-rated.

Cargo Weight:

The maximum weight of all the personal items and gear added to the Curb Weight of the motorhome or trailer.


This results from warm, moisture-laden air contacting cold window glass. Condensation inside an RV can cause mold and mildew. Keeping a roof vent open can help to reduce the humidity inside your RV, and using the fans when showering or using the stove can also help prevent excess moisture.


An electrical device for converting 120-volt AC power into 12-volt DC power. Most RVs with electrical hookups will have a converter, since many of the lights and some other accessories run on 12-volt DC.


The part of the trailer that attaches to the ball of the hitch.

Curb Weight:

The actual weight of a vehicle, motorhome or trailer, including all the standard equipment, with a full fuel tank, but without people or gear.


DC is a 12-volt direct current electrical system, the same as in a car.

Diesel Puller:

A motorhome with a diesel engine mounted in the front of the vehicle. Also known simply as a Puller.

Diesel Pusher:

A motorhome with the diesel engine mounted in the rear of the vehicle. Also known simply as a Pusher.


A booth-like dining area. The table is usually designed to drop down to convert into an extra bed.


The vehicle you are towing with your motorhome. It is also known as a Toad.


A rubber ring that seals one’s dump hose and the campsite sewer connection so that gases and odors do not escape. Sewer doughnuts are required in many locations.

Dry Camping:

Also known as boondocking, dry camping refers to camping without any hookups to electricity, sewer or water. (While dry camping, you still have electricity from your RV batteries, and water from your freshwater tank.)

Dry Weight:

The weight of the RV without any fuel, freshwater, propane or passengers.

DSI Ignition (Direct spark ignition):

This is a method of igniting the main burner on a propane appliance. The burner is lit via an electrical spark, and the flame is monitored by an electronic circuit board. This ignition system is used in refrigerators, furnaces and water heaters.

Dual Electrical System:

An RV with lights and appliances which operate on 12-volt battery power when dry camping, and with a converter on 110 AC current when plugged in at campgrounds or an onboard generator.


A pickup truck or motorhome with four tires on the rear axle.

Ducted AC:

Air conditioning with a ducting system in the ceiling. This will supply cooled air throughout the RV.

Ducted Heat:

Warm air from the furnace circulating through a ducting system located in the floor.

Dump Station:

A facility for dumping or emptying your black and gray holding tanks. You can usually often find fresh water at the dump station.

Equalizing Hitch:

A hitch that uses spring bars placed under tension, to distribute a portion of the trailer’s hitch weight to the tow vehicle’s front axle and the trailer’s axles. This hitch is also known as a weight distributing hitch.


Another name for a fifth-wheel RV.


Family Motor Coach Association

Fresh Tank:

The tank for freshwater that can be stored for later use.

Full Hookup:

A campground with electric, water and sewer hookups at each campsite.

FullTimers or FullTiming:

People who live in their RV fulltime, or at least the most of their time.


A large electrical appliance powered by gas or diesel, and sometimes propane, for generating 120-volt AC power.

Gray Tank:

The tank that holds wastewater from the sinks and shower, until you can dump it.

Gray Water:

Wastewater from the sinks and shower.

Gross Axle Weight Rating (GAWR):

The manufacturer’s maximum load weight, that can be placed on the axle. If an axle has a 3500-lb. GAWR and the RV have two axles (tandem axles), then the RV would have a Gross Vehicle Weight Rating (GVWR) of 7000 lbs.

Gross Combined Weight (GCW):

The combined weight of the tow vehicle and the trailer.

Gross Combined Weight Rating (GCWR)

: The manufacturer’s maximum load weight allowed for the trailer and tow vehicle. This rating includes the weight of the trailer, tow vehicle, fuel, water, propane, supplies, and passengers.

(GTW) Gross Trailer Weight:

The weight of the trailer, fully loaded with gear, in its actual towing condition.

(GVW) Gross Vehicle Weight:

The total weight of the vehicle.

(GVWR) Gross Vehicle Weight Rating:

The manufacturer’s maximum load weight allowed for the vehicle. This includes the weight of the vehicle plus fuel, water, propane, supplies, and passengers.

Heat Exchanger:

A heat exchanger transfers heat from one source to another, such as inside your furnace.

Heat Strip:

A heat strip is an electric heating element located in the air conditioning system, with the warm air distributed by the air conditioner fan and ducting system.

Hitch Rating:

The weight that the hitch is designed to handle.

Hitch Weight:

The amount of a trailer’s weight rests on the tow vehicle’s hitch. For travel trailers, this weight should be 10% to 15% of the total weight of the trailer. For 5th wheels, this weight should be 15% to 20% of the total weight of the trailer.

Holding Tanks:

There are three different holding tanks on most RVs; Fresh Water, Gray Water, and Black Water. The freshwater tank holds the water you will use for drinking and washing when boondocking. The Gray Water tank holds water from your sinks and shower, and the black water tank holds the waste from your toilet.


The types of hookups available at campgrounds are electric, water and sewer. If all three are available, it is termed full hookup. Hookups may also include telephone and cable TV in some campgrounds.

Hula Skirt:

A skirt placed on the back bumper of a motorhome to stop debris thrown up from the rear wheels from damaging vehicles behind the motorhome, or the vehicle you are towing.


An electrical appliance that changes 12 volt battery power to 120 volt AC power. It is used when “boondocking” to power certain 120v AC appliances, like a microwave oven. The amount of available power depends on the storage capacity of the batteries, and the wattage rating of the inverter.


A sandwich of structural frame members, wall paneling, insulation and exterior covering, adhesive-bonded under pressure or heat, to form the RV’s walls, floor, and roof.


The amount of weight an object supports.

LP Gas (Liquefied Petroleum Gas, also known as Propane):

LP gas is used to fuel appliances in the RV, such as the stove, oven, water heater, and refrigerator. Propane tanks are usually rated as pounds or gallons.

Motor Coach:

A motorhome that is built on a bus style chassis.

Net Carrying Capacity (NCC):

Also called the payload capacity, this is the maximum weight of fuel, water, propane, supplies, and passengers that can be added to an RV without exceeding the Gross Vehicle Weight Rating (GVWR).

Part Timers:

People who use their RV more than just a few weekend trips a year, but who still use it less than full time.

Payload Capacity:

The maximum allowable weight that can be in or on a vehicle, including all cargo and accessories, fuel, freshwater, propane, passengers and hitch loads.


A pilot is a small flame used to light the main burner of a propane-fired appliance, as the thermostat calls for heat. Pilots are used in furnaces, water heaters, refrigerators, ovens, and stovetops.

Pin Weight:

Also called King Pin Weight, this is the downward force exerted on the kingpin by a fifth-wheel hitch coupler. In most cases, it should be about 15 to 25 percent of GTW.

Pop Out:

A room in an RV that pops out for additional living space.

Pop Up:

Another name for a folding camping trailer.


The up and down motion in an RV while traveling.

Primative Camping:

Camping without use of hookups. (another name for boondocking and dry camping)


LPG, or liquid petroleum gas, used in RVs for heating, cooking and refrigeration.

Pull Through:

A campsite that allows you to pull through, rather than back in. This is a preferred one night site for those towing a car, since you won’t have to unhitch.


A slang term for a motorhome with a front-mounted diesel engine.


A slang term for a motorhome with a rear-mounted diesel engine.


The maximum allowable limits determined by the manufacturer in the design of the vehicle.


The part of the hitch that permits a hitch bar to be inserted.


What many RVers call their RVs, trucks and tow cars combined.

Roof Air Conditioner:

Air conditioning unit mounted on roof of RV.


Short for Recreational Vehicle, which includes all motorhomes, vans, trailers and 5th wheels. Persons using them are RVers.


Recreational Vehicle Dealers Association


Recreational Vehicle Industry Association


Recreational Vehicle Rental Association

Safety Chains:

A set of chains attached to both the trailer A-Frame and the tow vehicle while towing, intended to keep the trailer attached to the tow vehicle in the event of a hitch failure, preventing the trailer from completely separating from the truck. Safety chains are also used on motorhomes towing a car.

Screen Room:

A screen enclosure that attaches to the exterior of an RV, usually to the awning, for a screened living area outside.

Self Contained:

An RV that needs no external electrical, sewer or water hookup, allowing it to park overnight anywhere.

Semi-Modern Camping:

Camping with partial hookups, usually just electrical.

Sewer Doughnut:

A rubber ring that seals the RV sewer hose and the campsite’s sewer connection, so gases and odors don’t escape. Sewer doughnuts are required in many locations.

Shore Power:

Electricity provided to the RV from an external source, such as a campground hookup.

Slide In:

A type of camper that mounts on a truck bed, because this type of camper slides into the truck bed.

Slide Out:

An area in your RV that slides out, to make additional space for living.


A slang term for a slider hitch.

Slider Hitch:

A sliding hitch is used on short-bed pickup trucks allowing them to tow fifth-wheel trailers, with sufficient clearance to make turns without having the trailer hit the cab of the truck.


Monitors the pilot light of a propane appliance. If the pilot flame is extinguished, the thermocouple causes the gas valve to shut off the gas to both the pilot light and the main burner.

Tip Out:

An area or room in an RV that tips out for additional living space. The Tip Out was generally used in older RVs, newer RVs mainly use a slide-out.


The term for a vehicle that is “towed” with your motorhome. It is also known as a Dinghy.

Tongue Weight (TW):

Tongue weight is the downward force exerted on the hitch ball by the trailer coupler.

Tow Bar:

A bar used to connect a towed vehicle to the motorhome, for towing with all four wheels on the ground.

Trailer Brakes:

Brakes that are built into the trailer, and are activated by an electric signal from the truck.

Transmission Cooler:

A heat exchanger is similar to a small radiator, through which automatic transmission is cooled.

Triple Towing:

The term used for three vehicles hitched together, usually, a tow vehicle pulling two separate trailers, such as a truck pulling a travel trailer, with a boat behind that.


The RV’s underfloor surface, which is protected by a weatherproofed material.

Unloaded Vehicle Weight (UVW):

Sometimes called Dry Weight, it’s the weight of the RV without fuel, water, propane, supplies, and passengers. The manufacturer’s UVW will not include any dealer installed options.

Waste Water Tanks:

The gray water tank holds the wastewater from the sinks and showers. The black water tank holds waste from the toilet.

Weight Carrying Hitch:

A hitch designed to accept the entire hitch weight of the trailer. This hitch is also known as a deadweight hitch.

Weight Distributing Hitch:

A hitch that uses spring bars placed under tension, to distribute a portion of the trailer’s hitch weight to the tow vehicle’s front axle and the trailer’s axles. This hitch is also known as an equalizing hitch.

Wet Weight:

The weight of the RV with the fuel, freshwater and propane tanks full.


The distance between the center lines of the primary axles of a vehicle. If a motor home includes a tag axle, the distance is measured from the front axle to the center point between the drive and tag axles.

Wide Body:

The term for an RV exceeding the normal 8 foot width. Wide Bodies are usually 102″ (8′ 6″) wide.

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