The Collaborative International Dictionary
Rhino-
Rhino- \Rhi"no-\ A combining form from Greek ??, ???, the nose, as in rhinolith, rhinology.
Douglas Harper's Etymology Dictionary
rhino-
before vowels rhin-, word-forming element meaning "nose, of the nose," from Greek rhino-, comb. form of rhis "nose," which is of uncertain origin.
Wiktionary
rhino-
pre. Of the nose.