Meaning

noun a full supply

noun (often followed by `of') a large number or amount or extent

adverb as much as necessary; ; (`plenty' is nonstandard)

originFrom Anglo-Norman plent(é) + -y, from Middle English plentie, plentee, plente, from Anglo-Norman plenté, from Old French plenté, from Latin plēnitātem, accusative of plēnitās (“fullness”), from plenus (“complete, full”), from Proto-Indo-European *pl̥h₁nós (“full”), from which English full also comes, via Proto-Germanic. Related to the Latin derivatives replenish, plenary, complete, deplete,…

Etymology from Wiktionary, CC BY-SA 3.0