unit

UK: /ˈjuːnɪt/ US: /ˈjunɪt/ ,(yo̅o̅′nit)

WordReference Random House Learner's Dictionary of American English © 2026

u•nit /ˈyunɪt/   n. [countable]

1. a single thing;
   one person or thing.
2. any group of things or persons thought of as a single thing:
   The team formed a unit.
3. one of the individuals, parts, or elements into which a whole may be divided.
4. one of a number of things that are identical or equivalent in function or form:
   a rental unit.
5. a machine, part, or system of machines having a specified purpose, often an apparatus or piece that is part of a bigger piece:
   a heating unit.
6. Weights and Measures a specified amount of a quantity, as of length, volume, or time, by comparison with which any other quantity of the same kind is measured:
   a unit of measurement, as an inch.
7. Mathematics the least positive integer;
   one.

See -uni-.

WordReference Random House Unabridged Dictionary of American English © 2026

u•nit  (yo̅o̅′nit), n. 

1. a single thing or person.
2. any group of things or persons regarded as an entity:
   They formed a cohesive unit.
3. one of the individuals or groups that together constitute a whole;
   one of the parts or elements into which a whole may be divided or analyzed.
4. one of a number of things, organizations, etc., identical or equivalent in function or form:
   a rental unit; a unit of rolling stock.
5. any magnitude regarded as an independent whole;
   a single, indivisible entity.
6. Weights and Measures Also called dimension. any specified amount of a quantity, as of length, volume, force, momentum, or time, by comparison with which any other quantity of the same kind is measured or estimated.
7. the least positive integer;
   one.
8. Mathematics Also called unit's place. 
   • (in a mixed number) the position of the first digit to the left of the decimal point.
   • (in a whole number) the position of the first digit from the right of the decimal point.
9. a machine, part, or system of machines having a specified purpose;
   apparatus:
   a heating unit.
10. Education a division of instruction centering on a single theme.
11. Military an organized body of soldiers, varying in size and constituting a subdivision of a larger body.
12. Medicine
    • the measured amount of a substance necessary to cause a certain effect;
      a clinical quantity used when a substance cannot be readily isolated in pure form and its activity determined directly.
    • the amount necessary to cause a specific effect upon a specific animal or upon animal tissues.
13. Mathematics
    • an identity element.
    • an element in a group, ring, etc., that possesses an inverse.

• 1570; coined by John Dee as a translation of Greek mónas (previously rendered as unity); perh. influenced by digit

Unit., 

1. Unitarian.

Collins Concise English Dictionary © HarperCollins Publishers::

unit / ˈjuːnɪt/ noun

1. a single undivided entity or whole
2. any group or individual, esp when regarded as a basic element of a larger whole
3. a mechanical part or integrated assembly of parts that performs a subsidiary function: a filter unit
4. a complete system, apparatus, or establishment that performs a specific function: a production unit
5. a subdivision of a larger military formation
6. Also called: unit of measurement a standard amount of a physical quantity, such as length, mass, energy, etc, specified multiples of which are used to express magnitudes of that physical quantity: the second is a unit of time
7. the amount of a drug, vaccine, etc, needed to produce a particular effect
8. a standard measure used in calculating alcohol intake and its effect
9. (modifier) having a value defined as one for the system: unit vector
10. Also called: unit set a set having a single member
11. short for home unit
13. a self-propelled railcar

Etymology: 16th Century: back formation from unity, perhaps on the model of digit