The Collaborative International Dictionary of English v.0.48:

Invertible \In*vert"i*ble\, a. [From Invert.]
   1. Capable of being inverted or turned inside out.
      [1913 Webster]

   2. (Chem.) Capable of being changed or converted; as,
      invertible sugar.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Invertible \In*vert"i*ble\, a. [Pref. in- not + L. vertere to
   turn + -ible.]
   Incapable of being turned or changed.
   [1913 Webster]

         An indurate and invertible conscience.   --Cranmer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

invertible
    adj 1: having an additive or multiplicative inverse [ant: non-
           invertible]