The Collaborative International Dictionary of English v.0.48:

Logotype \Log"o*type\, n. [Gr. lo`gos word + -type.] (Print.)
   A single type, containing two or more letters; as, [ae],
   \[oe], [AE], [filig], [fllig], [ffllig], etc.; -- called also
   ligature.
   [1913 Webster]

WordNet (r) 3.0 (2006):

logotype
    n 1: a company emblem or device [syn: logo, logotype]