The Collaborative International Dictionary of English v.0.48:

Microtome \Mi"cro*tome\ (m[imac]"kr[-o]*t[=o]m), n. [Micro- +
   Gr. te`mnein to cut.]
   An instrument for making very thin sections for microscopical
   examination.
   [1913 Webster] Microtomic

WordNet (r) 3.0 (2006):

microtome
    n 1: scientific instrument that cuts thin slices of something
         for microscopic examination