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.
(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.
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/Medical.
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.
Mathematics.
a.
an identity element.
b.
an element in a group, ring, etc., that possesses an inverse.
[Origin: 1570; coined by John Dee as a trans. of Gk mónas (previously rendered as unity); perh. influenced by digit]
astronomical unit (AU), mean distance between the earth and sun; one AU is c.92,960,000 mi (149,604,970 km). The astronomical unit is the principal unit of measurement within the solar system, e.g., Mercury is just over 1/3 AU and Pluto is about 39 AU from the sun.
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