The Collaborative International Dictionary of English v.0.48:

Cottise \Cot"tise\ (k[o^]t"t[i^]s), n. [Cf. F. c[^o]t['e] side,
   L. costa rib.] (Her.)
   A diminutive of the bendlet, containing one half its area or
   one quarter the area of the bend. When a single cottise is
   used alone it is often called a cost. See also
   Couple-close.
   [1913 Webster]