Definition of swallowtail

• n. - A kind of tenon or tongue used in making joints. See Dovetail.
• n. - A species of willow.
• n. - An outwork with converging sides, its head or front forming a reentrant angle; -- so called from its form. Called also priestcap.
• n. - A swallow-tailed coat.
• n. - An arrow.
• n. - Any one of numerous species of large and handsome butterflies, belonging to Papilio and allied genera, in which the posterior border of each hind wing is prolongated in the form of a long lobe.