Lewis Short
collīsĭo | conl- (noun F) : (), , collido
* A dashing or striking together, a concussion, shock: partūs abjecti,Just. 11, 12, 6.
* Transf., of letters in a word: πνεῖν, χεἰν, ῥεῖν, non sunt integra, sed ex collisione contracta. Macr. Diff. 19, § 17.
Charlton T. Lewis, Charles Short, A Latin Dictionary