{Expanding bit}, {Expanding drill} (Mech.), a bit or drill
made adjustable for holes of various sizes; one which can
be expanded in diameter while boring.
{Expanding pulley} (Mach.), a pulley so made, as in sections,
that its diameter can be increased or diminished.
Then with expanded wings he steers his flight.
--Milton.
2. To cause the particles or parts of to spread themselves or
stand apart, thus increasing bulk without addition of
substance; to make to occupy more space; to dilate; to
distend; to extend every way; to enlarge; -- opposed to
{contract}; as, to expand the chest; heat expands all
bodies; to expand the sphere of benevolence.
3. (Math.) To state in enlarged form; to develop; as, to
expand an equation. See {Expansion}, 5.