The Collaborative International Dictionary of English v.0.48:

Apteral \Ap"ter*al\, a.
   1. (Zool.) Apterous.
      [1913 Webster]

   2. (Arch.) Without lateral columns; -- applied to buildings
      which have no series of columns along their sides, but are
      either prostyle or amphiprostyle, and opposed to
      peripteral. --R. Cyc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

apteral
    adj 1: having columns at one or both ends but not along the
           sides [ant: peripteral]
    2: (of insects) without wings [syn: apterous, apteral]