Webster’s Revised Unabridged Dictionary · 1913
Gregarious
Gre·ga′ri·ous (grē·gā′rĭ·ŭs), a. [L. gregarius, fr. grex, gregis, herd; cf. Gr. ἀγείρειν 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.
— Gre·ga′ri·ous·ly, adv. — Gre·ga′ri·ous·ness, n.