Source : Webster's Revised Unabridged Dictionary (1913)

Gregarious \Gre*ga"ri*ous\, a. [L. gregarius, fr. grex, gregis,
   herd; cf. Gr. ? to assemble, Skr. jar to approach. Cf.
   {Congregate}, {Egregious}.]
   Habitually living or moving in flocks or herds; tending to
   flock or herd together; not habitually solitary or living
   alone. --Burke.

         No birds of prey are gregarious.         --Ray.

Source : WordNet®

gregarious
     adj 1: tending to form a group with others of the same kind;
            "gregarious bird species"; "man is a gregarious
            animal" [ant: {ungregarious}]
     2: seeking and enjoying the company of others; "a gregarious
        person who avoids solitude"