Meaning

adjective used especially of drugs or muscles that work together so the total effect is greater than the sum of the two (or more)

adjective capable of acting on or influencing each other

originEtymology tree Proto-Indo-European *h₁én Proto-Indo-European *h₁entér Proto-Italic *n̥ter Latin inter Latin inter-bor. English inter- Proto-Indo-European *h₂eǵ- Proto-Indo-European *-eti Proto-Indo-European *h₂éǵeti Proto-Italic *agō Latin agō Proto-Indo-European *-wós Proto-Indo-European *-iHwósder. Latin -īvus ▲ Ancient Greek ἐνεργητῐκός (energētĭkós)sl. Latin āctīvusbor. Old French actifbor.…

Etymology from Wiktionary, CC BY-SA 3.0