unit

A unit is a fixed standard amount or a single person, group, thing or number. (noun)

An example of a unit is a single apartment in an apartment building.

See unit in Webster's New World College Dictionary

noun

1. the smallest whole number; one
2. a magnitude or number regarded as an undivided whole
3. the number in the position just to the left of the decimal point
any fixed quantity, amount, distance, measure, etc. used as a standard; specif.,
1. ☆ a fixed amount of work used as a basis in awarding scholastic credits, usually determined by the number of hours spent in class
2. the amount of a drug, vaccine, serum, or antigen needed to produce a given result, as on a certain animal or on animal tissues
1. a single person, group, or thing, esp. as distinguished from others or as part of a whole
2. a single, distinct part or object, esp. one used for a specific purpose: the lens unit of a camera
3. a single residence, as an apartment, that is part of a complex: a rental unit
Mil. an organized body of troops, airplanes, etc. forming a subdivision of a larger body

Unitarian

See unit in American Heritage Dictionary 4

(yo͞oˈnĭt)

noun

An individual, group, structure, or other entity regarded as an elementary structural or functional constituent of a whole.
A group regarded as a distinct entity within a larger group.
a. A mechanical part or module.
b. An entire apparatus or the equipment that performs a specific function.
A precisely specified quantity in terms of which the magnitudes of other quantities of the same kind can be stated.
Medicine The quantity of a vaccine, serum, drug, or other agent necessary to produce a specific effect.
a. A fixed amount of scholastic study used as a basis for calculating academic credits, usually measured in hours of classroom instruction or laboratory work.
b. A section of an academic course focusing on a selected theme: a unit on Native Americans.
The number immediately to the left of the decimal point in the Arabic numeral system.
Mathematics
a. The lowest positive whole number; one.
b. An element of a ring with a multiplicative inverse.