The Collaborative International Dictionary of English v.0.48:

Cutlass \Cut"lass\ (k[u^]t"las), n.; pl. Cutlasses (-[e^]z).
   [F. coutelas (cf. It. coltellaccio), augm. fr. L. cuttellus a
   small knife, dim. of culter knife. See Colter, and cf.
   Curtal ax.]
   A short, heavy, curving sword, used in the navy. See Curtal
   ax.
   [1913 Webster] cutlass fish