\Spine"tail`\, n. (Zo["o]l.)
(a) Any one or several species of swifts of the genus
    {Acanthylis}, or {Ch[ae]tura}, and allied genera, in
    which the shafts of the tail feathers terminate in rigid
    spines.
(b) Any one of several species of South American and Central
    American clamatorial birds belonging to {Synallaxis} and
    allied genera of the family {Dendrocolaptid[ae]}. They
    are allied to the ovenbirds.
(c) The ruddy duck. [Local, U.S.]