the reciprocal of the tangent ; specif.
the ratio of the adjacent side of a given acute
angle in a right
triangle to the opposite side
Webster’s New World College Dictionary, 4th Edition. Copyright © 2010 by
Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'cotangent'ModL cotangens < co. tangens, short for complementi tangens, lit., tangent of the complement