noun a species of willow.
2. swallowtail ·noun a swallow-tailed coat.
3. swallowtail ·noun an arrow.
4. swallowtail ·noun a kind of tenon or tongue used in making joints. ·see dovetail.
5. swallowtail ·noun an outwork with converging sides, its head or front forming a reentrant angle;
so called from its form. called also priestcap.
6. swallowtail ·noun 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.