Expanding \Ex*pand"ing\, a. That expands, or may be expanded; extending; spreading; enlarging.

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.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Expand \Ex*pand"\, v. t. [imp. & p. p. Expanded; p. pr. & vb. n. Expanding.]

[L. expandere, expansum; ex out + pandere to spread out, to throw open; perh. akin to E. patent. Cf. Spawn.]

1. To lay open by extending; to open wide; to spread out; to diffuse; as, a flower expands its leaves.

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.

Source: Webster's Revised Unabridged Dictionary (1913)