The Collaborative International Dictionary of English v.0.48:

Remora \Rem"o*ra\ (r?m"?*r?), n. [L.: cf. F. r['e]mora.]
   [1913 Webster]
   1. Delay; obstacle; hindrance. [Obs.] --Milton.
      [1913 Webster]

   2. (Zool.) Any one of several species of fishes belonging to
      Echeneis, Remora, and allied genera. Called also
      sucking fish.
      [1913 Webster]

   Note: The anterior dorsal fin is converted into a large
         sucking disk, having two transverse rows of lamellae,
         situated on the top of the head. They adhere firmly to
         sharks and other large fishes and to vessels by this
         curious sucker, letting go at will. The pegador, or
         remora of sharks (Echeneis naucrates), and the
         swordfish remora (Remora brachyptera), are common
         American species.
         [1913 Webster]

   3. (Surg.) An instrument formerly in use, intended to retain
      parts in their places. --Dunglison.
      [1913 Webster]

WordNet (r) 3.0 (2006):

remora
    n 1: marine fishes with a flattened elongated body and a sucking
         disk on the head for attaching to large fish or moving
         objects [syn: remora, suckerfish, sucking fish]