\An`al*lag*mat"ic\, a. [Gr. 'an priv. + ? a
change.] (Math.)
Not changed in form by inversion.

{Anallagmatic curves}, a class of curves of the fourth degree
   which have certain peculiar relations to circles; --
   sometimes called {bicircular quartics}.

{Anallagmatic surfaces}, a certain class of surfaces of the
   fourth degree.