Source : Webster's Revised Unabridged Dictionary (1913)

Feud \Feud\, n. [OE. feide, AS. f?h?, fr. f[=a]h hostile; akin
   to OHG. f?hida, G. fehde, Sw. fejd, D. feide; prob. akin to
   E. fiend. See Foe.]
   1. A combination of kindred to avenge injuries or affronts,
      done or offered to any of their blood, on the offender and
      all his race.

   2. A contention or quarrel; especially, an inveterate strife
      between families, clans, or parties; deadly hatred;
      contention satisfied only by bloodshed.

            Mutual feuds and battles betwixt their several
            tribes and kindreds.                  --Purchas.

   Syn: Affray; fray; broil; contest; dispute; strife.

Feud \Feud\, n. [LL. feudum, feodum prob. of same origin as E.
   fief. See {Fief}, {Fee}.] (Law)
   A stipendiary estate in land, held of superior, by service;
   the right which a vassal or tenant had to the lands or other
   immovable thing of his lord, to use the same and take the
   profists thereof hereditarily, rendering to his superior such
   duties and services as belong to military tenure, etc., the
   property of the soil always remaining in the lord or
   superior; a fief; a fee.

Source : WordNet®

feud
     n : a bitter quarrel between two parties
     v : carry out a feud; "The two professors have been feuding for
         years"