Influential

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late 16th century (referring to astral influence): from medieval Latin influentia (see influence).

wiktionary

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From Medieval Latin īnfluentiālis, from īnfluentia + -ālis. Synchronically analyzable as influence +‎ -ial.

etymonline

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influential (adj.)

"powerful, having influence," 1650s, from Medieval Latin influentialis, from influentia (see influence (n.)). Earlier in an astrological sense (1560s). Related: Influentially.