Expanding

[Sarah]

That expands, or may be expanded; extending; spreading;enlarging. Expanding bit, Expanding drill (Mech.), a bit or drillmade adjustable for holes of various sizes; one which can be expandedin diameter while boring.-- Expanding pulley (Mach.), a pulley so made, as in sections, thatits diameter can be increased or diminished.

[Sonia]

present participle of expand