cotangent

UK: /kəʊˈtændʒənt/ US: (kō tan′jənt, kō′tan′-)

WordReference Random House Unabridged Dictionary of American English © 2025

co•tan•gent  (kō tan′jənt, kō′tan′-), n. [Trig.]

1. Mathematics (in a right triangle) the ratio of the side adjacent to a given angle to the side opposite.
2. Mathematics the tangent of the complement, or the reciprocal of the tangent, of a given angle or arc. Abbr.: cot, ctn 

  Also, co•tan  (kō′tan′). 

• Neo-Latin cotangent- (stem of cotangēns). See co-, tangent
• 1625–35;

co•tan•gen•tial  (kō′tan jen′shəl), adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

cotangent / kəʊˈtændʒənt/ noun

1. (of an angle) a trigonometric function that in a right-angled triangle is the ratio of the length of the adjacent side to that of the opposite side; the reciprocal of tangent