Source : Webster's Revised Unabridged Dictionary (1913)

Infix \In*fix"\, v. t. [imp. & p. p. {Infixed}; p. pr. & vb. n.
   {Infixing}.] [L. infixus, p. p of infigere to infix; pref.
   in- in + figere to fix: cf. F. infixer. See {Fix}.]
   1. To set; to fasten or fix by piercing or thrusting in; as,
      to infix a sting, spear, or dart. --Shak.

            The fatal dart a ready passage found, And deep
            within her heart infixed the wound.   --Dryden.

   2. To implant or fix; to instill; to inculcate, as
      principles, thoughts, or instructions; as, to infix good
      principles in the mind, or ideas in the memory.

Infix \In"fix\, n.
   Something infixed. [R.] --Welsford.

Source : WordNet®

infix
     v 1: put or introduce into something; "insert a picture into the
          text" [syn: {insert}, {enter}, {introduce}]
     2: attach a morpheme into a stem word

infix
     n : an affix that is inserted inside the word