The Collaborative International Dictionary of English v.0.48:

Monotype \Mon"o*type\, Monotypic \Mon`o*typ"ic\, a. [Mono- +
   -type: cf. F. monotype.] (Biol.)
   Having but one type; containing but one representative; as, a
   monotypic genus, which contains but one species.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Monotype \Mon"o*type\,
   1. [Mono- + -type.]

   1. (Biol.) The only representative of its group, as a single
      species constituting a genus.
      [Webster 1913 Suppl.]

   2. A print (but one impression can be taken) made by painting
      on metal and then transferring the painting to paper by
      pressure; also, the process of making such prints.
      [Webster 1913 Suppl.]

   3. A kind of keyboard-operated typesetting and casting
      machine that makes and sets separate characters.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

monotype
    n 1: (biology) a taxonomic group with a single member (a single
         species or genus)
    2: a typesetting machine operated from a keyboard that sets
       separate characters