/yooh"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. 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. Also called unit's place .
a. (in a mixed number) the position of the first digit to the left of the decimal point.
b. (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. Educ. a division of instruction centering on a single theme.
11. Mil. an organized body of soldiers, varying in size and constituting a subdivision of a larger body.
12. Med.
a. 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.
b. the amount necessary to cause a specific effect upon a specific animal or upon animal tissues.
13. Math.
a. an identity element.
b. an element in a group, ring, etc., that possesses an inverse.
[ 1570; coined by John Dee as a trans. of Gk mónas (previously rendered as unity ); perh. influenced by digit ]