fourth month, c. 1300, aueril, from Old French avril (11c.), from Latin (mensis) Aprilis, second month of the ancient Roman calendar, from a stem of uncertain origin and meaning, with month-name suffix -ilis as in Quintilis, Sextilis (the old names of July and August).
Perhaps based on Apru, an Etruscan borrowing of Greek Aphrodite. Or perhaps *ap(e)rilis "the following, the next," from its place as the second month of the old Roman calendar, from Proto-Italic *ap(e)ro-, from PIE *apo- "away, off" (see apo-; compare Sanskrit aparah "second," Gothic afar "after"). Old folk etymology connected it with Latin aperire "to open."
In English in Latin form from mid-12c.; it replaced Old English Eastermonað, which was named for a fertility goddess (see Easter). Re-spelled in Middle English on Latin model (apprile, first attested late 14c.).