Etymology
Advertisement
unit (n.)
1560s, "single number regarded as an undivided whole," alteration of unity on the basis of digit. Popularized in John Dee's English translation of Euclid, to express Greek monas (Dee says unity formerly was used in this sense). Meaning "single thing regarded as a member of a group" is attested from 1640s. Extended sense of "a quantity adopted as a standard of measure" is from 1738. Sense of "group of wards in a hospital" is attested from 1893.
Related entries & more 
Advertisement
photon (n.)

"unit of electromagnetic radiation," 1926, from photo- "light" + -on "unit." Related: Photonic.

Related entries & more 
unitary (adj.)
1847, "characterized by unity or uniformity;" 1865, "of or relating to a unit;" see unit + -ary.
Related entries & more 
B.T.U. 

1889 as an abbreviation of British Thermal Unit (1862), a commercial unit of electrical energy (the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit); the French Thermal Unit is the amount of heat required to raise 1 kilogram of water 1 degree centigrade. Also from 1889 as an abbreviation of Board of Trade Unit, in electicity "1,000 watt hours."

Related entries & more 
monad (n.)

1610s, "unity, arithmetical unit," 1610s, from Late Latin monas (genitive monadis), from Greek monas "unit," from monos "alone" (from PIE root *men- (4) "small, isolated"). In Leibnitz's philosophy, "an ultimate unit of being, a unit of the universal substance" (1748); he apparently adopted the word from Giordano Bruno's 16c. metaphysics, where it referred to a hypothetical primary indivisible substance at once material and spiritual. Related: Monadic; monadism.

Related entries & more 
Advertisement
sone (n.)

unit of loudness, 1936, from Latin sonus "sound," from PIE root *swen- "to sound."

Related entries & more 
picosecond (n.)

unit of time equal to one trillionth of a second, 1966, from pico- + second (n.).

Related entries & more 
megavolt (n.)

unit of measure equivalent to one million volts, 1868, from mega- "one million" + volt.

Related entries & more 
lira (n.)
Italian monetary unit, 1610s, from Italian lira, literally "pound," from Latin libra "pound (unit of weight);" see Libra, and compare livre. There also was a Turkish lira.
Related entries & more 
cpu 

also c.p.u., by 1970, abbreviation of central processing unit.

Related entries & more