Meaning

noun any of several Old World tropical aromatic annual or perennial herbs of the genus Ocimum

noun (Roman Catholic Church) the bishop of Caesarea who defended the Roman Catholic Church against the heresies of the 4th century; a saint and Doctor of the Church (329-379)

noun leaves of the common basil; used fresh or dried

originInherited from Middle English basile, from Middle French basile, from Old French basile, from Medieval Latin basilicum, from Ancient Greek βασιλικόν (basilikón, “royal”), from βασιλεύς (basileús, “king”). Doublet of basilic, basilicon, and basilicum; further related to basileus, basilean, and basileiolatry.

Etymology from Wiktionary, CC BY-SA 3.0