1620s, from French influx (16c.) or directly from Late Latin influxus "a flowing in," from past participle stem of Latin influere "to flow in" (see influence (n.)). Originally of rivers, air, light, spiritual light, etc.; used of people from 1650s.
inflow
influence
influent
influential
influenza
influx
info-
info
infold
infomercial
inform