Source : Webster's Revised Unabridged Dictionary (1913)

Spinetail \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.]