The Collaborative International Dictionary of English v.0.48:
moo-cow \moo-cow\ n. a cow[1]; -- a child's word. See 1st cow[1], n. [WordNet 1.5]WordNet (r) 3.0 (2006):
moo-cow n 1: female of domestic cattle: "`moo-cow' is a child's term" [syn: cow, moo-cow]