Meaning

noun a straight line through a body or figure that satisfies certain conditions

noun the main stem or central part about which plant organs or plant parts such as branches are arranged

noun in World War II the alliance of Germany and Italy in 1936 which later included Japan and other nations

originEtymology tree Proto-Indo-European *h₂eǵ-? Proto-Indo-European *-os Proto-Indo-European *h₂eḱs-der. Proto-Italic *aksis Latin axisbor. English axis Borrowed from Latin axis (“axle, axis”) in the 16th century. Via Latin cognate with ala, aisle, atelier. Via Proto-Indo-European *h₂eḱs- cognate with inherited English axle and borrowed axo-, axon.

Etymology from Wiktionary, CC BY-SA 3.0