The Collaborative International Dictionary of English v.0.48:

Equiangular \E`qui*an"gu*lar\, a. [Equi- + angular. Cf.
   Equangular.]
   Having equal angles; as, an equiangular figure; a square is
   equiangular.
   [1913 Webster]

   Equiangular spiral. (Math.) See under Spiral, n.

   Mutually equiangular, applied to two figures, when every
      angle of the one has its equal among the angles of the
      other.
      [1913 Webster]