congregate (v.) Look up congregate at Dictionary.com
mid-15c., from Latin congregatus "flocking together," past participle of congregare "to herd together, collect in a flock, swarm; assemble," from com- "together" (see com-) + gregare "to collect into a flock, gather," from grex (genitive gregis) "a flock" (see gregarious). Related: Congregated; congregating.