COTANGENT
cotangent, cotan
(noun) ratio of the adjacent to the opposite side of a right-angled triangle
Source: WordNet® 3.1
Etymology
Noun
cotangent (plural cotangents)
(trigonometry) In a right triangle, the reciprocal of the tangent of an angle. Symbols: cot, ctg, or ctn
Source: Wiktionary
Co*tan"gent (k-tn"jent), n. Etym: [For co. tangens, an abbrev. of L.
complementi tangens. See Tangent.] (Trig.)
Definition: The tangent of the complement of an arc or angle. See Illust.
of Functions.
Source: Webster’s Unabridged Dictionary 1913 Edition