Source : Webster's Revised Unabridged Dictionary (1913)

Infangthef \In*fang"thef\, n. [AS. in-fangen-pe['o]f; in in,
   into + fangen taken (p. p. of f?n to take) + pe['o]f thief.]
   (O. Eng. Law)
   The privilege granted to lords of certain manors to judge
   thieves taken within the seigniory of such lords. --Cowell.