2. (Bot.) A species of willow.
3. (Fort.) An outwork with converging sides, its head or
front forming a re["e]ntrant angle; -- so called from its
form. Called also {priestcap}.
This Stultz coat, a blue swallowtail, with yellow
buttons. --Thackeray.
6. (Zo["o]l.) 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.
Note: The black swallowtail, or asterias (see {Papilio}), the
blue swallowtail, or philenor, the tiger swallowtail,
or turnus (see {Turnus}), and the zebra swallowtail, or
ajax (see under {Zebra}) are common American species.
See also {Troilus}.