aggregation (n.) Look up aggregation at Dictionary.com
early 15c., aggregacioun, originally in medicine, "formation of a pustule," from Medieval Latin aggregationem (nominative aggregatio), noun of action from past participle stem of Latin aggregare "collect, bring together," from ad "to" (see ad-) + gregare "to collect into a flock, gather," from grex (genitive gregis) "a flock" (see gregarious). From 1540s as "a combined whole;" 1560s as "act of collecting in an unorganized mass."