\Head"stock`\, n. (Mach.)
A part (usually separate from the bed or frame) for
supporting some of the principal working parts of a machine;
as:
(a) The part of a lathe that holds the revolving spindle and
    its attachments; -- also called {poppet head}, the
    opposite corresponding part being called a tailstock.
(b) The part of a planing machine that supports the cutter,
    etc.