spin·na·ker 
(spĭnə-kər)
(spĭnə-kər)n.
A large triangular headsail secured only at the corners, used on sailboats when running before the wind.
[Perhaps ultimately from Sphinx, name of the first yacht to use such a sail, or spin, to move rapidly (variant of Scots spene, to run before the wind; see SPINDRIFT).]
spinnaker