gregarious adj.

Proto-Indo-European root meaning "to gather." 

It forms all or part of: aggregate; aggregation; agora; agoraphobia; allegory; category; congregate; cram; egregious; gregarious; panegyric; paregoric; segregate.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit gramah "heap, troop;" Greek ageirein "to assemble," agora "assembly;" Latin grex "flock, herd," gremium "bosom, lap;" Old Church Slavonic grusti "handful," gramota "heap;" Lithuanian gurgulys "chaos, confusion," gurguolė "crowd, mass;" Old English crammian "press something into something else."

masc. proper name, popular in England and Scotland by mid-12c. (Pope Gregory I sent the men who converted the English to Christianity), nativization of Late Latin Gregorius, literally "wakeful" (equivalent to Latin Vigilantius), from Greek gregorios, a derivative of gregoros "to be watchful," from PIE root *ger- (2) "to be awake" (source also of Sanskrit jagarti "he is awake," Avestan agarayeiti "wakes up, rouses"). At times confused with Latin gregarius (see gregarious).