Know why cattywampus was trending last week?
word-forming element meaning "other, different," from comb. form of Greek heteros "the other (of two), another, different;" first element meaning "one, at one, together," from PIE *sem- "one;" the second cognate with the second element in Latin al-ter, Gothic an-þar, Old English o-ðer "other."
hetero- or heter-
Other; different: heterocellular.
A prefix that means "different" or "other," as in heterophyllous, having different kinds of leaves.