- (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.
- 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.
- an identity element.
- an element in a group, ring, etc., that possesses an inverse.
Origin of unit
- (usually plural)the first position in a place-value counting system, representing a single-digit numberin the decimal system the number 27 has 7 units and 2 tens
- (modifier)having a value defined as one for the systemunit vector
Word Origin for unit
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.