The Collaborative International Dictionary of English v.0.48:

Compositor \Com*pos"i*tor\, n. [L., an arranger.]
   1. One who composes or sets in order.
      [1913 Webster]

   2. (Print.) One who sets type and arranges it for use.
      [1913 Webster]

WordNet (r) 3.0 (2006):

compositor
    n 1: one who sets written material into type [syn: compositor,
         typesetter, setter, typographer]