Three is often joined with other words, forming compounds signifying divided into, composed of, or containing, three parts, portions, organs, or the like; as, three-branched, three-capsuled, three-celled, three-cleft, three-edged, three-foot, three-footed, three-forked, three-grained, three-headed, three-legged, three-mouthed, three-nooked, three-petaled, three-pronged, three-ribbed, three-seeded, three-stringed, three-toed, and the like.
Origin: OE. Thre, threo, thri, AS. Thri, masc, threo, fem. And neut.; akin to OFries. Thre, OS. Thria, threa, D. Drie, G. Drei, OHG. Dri, Icel. Thrir, Dan. & Sw. Tre, Goth. Threis, Lith. Trys, Ir, Gael. & W. Tri, Russ. Tri, L. Tres, Gr. Trei^s, Skr. Tri. 301. Cf. 3d Drilling, Tern, Third, Thirteen, Thirty, Tierce, Trey, Tri-, Triad, Trinity, Tripod.
(Science: mathematics) See rule.