What is "colatitude"

Colatitude \Co*lat"i*tude\ (?; 134), n. [Formed like cosine. See Cosine.] The complement of the latitude, or the difference between any latitude and ninety degrees.

n. (context astronomy English) The complement, in spherical coordinates, of a latitude (the difference between a latitude and 90°).

In spherical coordinates, colatitude is the complementary angle of the latitude, i.e. the difference between 90° and the latitude, where southern latitudes are denoted with a minus sign.