1650s, "cooperation," from Modern Latin synergia, from Greek synergia "joint work, assistance, help," from synergos "working together," related to synergein "work together, help another in work," from syn- "together" (see syn-) + ergon "work" (see urge (v.)). Meaning "combined activities of a group" is from 1847.
synergic syn·er·gic (sĭ-nûr'jĭk)
synergy syn·er·gy (sĭn'ər-jē)
The interaction of two or more agents or forces so that their combined effect is greater than the sum of their individual effects.