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Glossary of Bathtub Terms and Definitions

Selecting the right bathtub can be a frustrating process if you're not completely familiar with all the associated terminology. To help you navigate the vast world of tubs, created this helpful glossary of definitions for some of the most common bathtub-related terms. If you're confused about the difference between installation types, flummoxed by spec sheets or simply want to communicate better with your general contractor, you can brush up on your bathtub vocabulary right here.


A lightweight material used in the construction of bathtubs. Acrylic is more flexible than cast iron and is warmer to the touch.
Air Bath
A bathtub that releases millions of tiny bubbles through small holes in the bottom of the tub. Unlike whirlpool tubs which use powerful jets, air baths utilize blowers to create a gentle massage experience. Air baths are also referred to as using thermo-air massage.
The finished front facing side of a bathtub in alcove or 3-wall installations. May also be referred to as a skirt.
The process of using scents and fragrances to elicit a specific therapeutic response or reaction. Aromatherapy tubs feature diffusers that release your choice of essential oils to enhance relaxation during the bath experience.
The process of using sounds and music to elicit a specific therapeutic response or reaction. Audiotherapy tubs feature a built-in sound system that transforms the bathtub's shell into a sounding board for even distribution of sound.


Bathing Well
The interior of the tub where one sits during a bath.
The engine that pushes warm air into the tub for use with air baths.


Cast Iron
A material used in the construction of bathtubs where liquid iron is poured into a mold in the shape of the bathtub.
The process of using colored lights to elicit a specific therapeutic response or reaction. Chromatherapy tubs incorporate colored lights to enhance relaxation during the bath experience.
Refers to a bathtub that has four "feet" shaped like an animal's foot and claws, and which is free-standing in style rather than enclosed in an alcove or dropped into a tile enclosure
Typically refers to the handles or knobs on a tub faucet or filler that are used to adjust water flow and temperature. In some advanced bathtubs, controls may also refer to buttons on the tub or a separate remote control that are used to operate blowers, jets, aromatheraphy or other electronic features.


The horizontal perimeter (lip) of the tub. May also refer to the structure that surrounds a tub, especially an undermount or drop-in bathtub.
Drop-In Tub
A type of tub that is installed by being "dropped into" a pre-built tub surround or alcove. Drop-in bathtubs are designed with a finished top edge.


A faucet specifically designed for use in filling a tub with water. Tub fillers can be free-standing, deck mounted (for tubs with a surround) or wall-mounted.
Free-Standing Tub
A type of tub that is not attached to any walls and is installed through the floor instead. Clawfoot tubs are a type of free-standing bathtub, but not all free-standing tubs are clawfoot in design.
Full Immersion
Refers to bathtubs that are deeper than normal, allowing water to cover the bather up to their shoulders.


The process of relaxing the body through the use of water, especially in a bathtub or pool. Soaker, whirlpool and air baths all provide different types of hydrotherapy.


Infinity Edge
Refers to a tub designed so that water can be filled to the top edge, similar to an infinity pool. Water "overflows" into a gap between the inner and outer tub walls.


Jet (or Jets)
Mechanisms that push pressurized water into the tub for the purpose of massaging the body, typically found in whirlpool bathtubs. Air baths also use jets, through they are typically much smaller and produce less pressure.


Lift and Turn Drain
A drain that must be lifted and then turned to keep in the open position.


Maximum Fill
The maximum amount of water a bathtub can hold in gallons.


A mechanism on the inside wall of a bathtub that drains water once it reaches a certain height, ensuring the water doesn't flow over the edge of the tub. Some overflows also control the drain.


The engine that pushes warm water and air into a tub for use with whirlpool jets.


Shower Panel
A shower fixture that integrates a combination of showerheads, jets, temperature controls and volume controls into one unit for ease of use and the targeting of specific parts of the body.
The finished front facing side of a bathtub in alcove or 3-wall installations. May also be referred to as an apron.
Soaker Tub
A deep tub meant for soaking, typically designed without any whirlpool jets or other advanced features.
Spec Sheet
A document that explains a product's various features and measurements (specifications). Spec sheets typically include a diagram of the product and sometimes include installation instructions.
A structure or platform made of tile or a natural stone slab that surrounds a bathtub. Tub surrounds typically hide the majority of the bathtub's exterior and give the appearance of the tub being "built into" the surrounding tile or stone.


Tile Flange
A perpendicular edge or lip found on some bathtubs used to create a water-tight seal with the wall, typically used in alcove or 3-wall installations.
Tip Toe Drain
Also called a toe tap drain, a drain that can be activated by the bather's foot.
Tub Surround
See "Surround"
Tub Filler
See "Filler"


Undermount Tub
Sometimes referred to as an underdeck tub, undermount tubs are installed underneath a pre-existing tub surround. Undermount bathtubs are designed so that the top edge of the tub is flush with and typically hidden by tile or a natural stone slab. Many undermount bathtubs can also be used as drop-in tubs.


Whirlpool Tub
Refers to a bathtub that utilizes powerful jets for the purpose of massaging the body.