The Collaborative International Dictionary of English v.0.48:

Guillotine \Guil"lo*tine`\ (g[i^]l`l[-o]*t[=e]n"), v. t. [imp. &
   p. p. Guillotined; p. pr. & vb. n. Guillotining.] [Cf. F.
   guillotiner.]
   To behead with the guillotine.
   [1913 Webster]