The Collaborative International Dictionary of English v.0.48:
Swell \Swell\, n.
1. The act of swelling.
2. Gradual increase. Specifically:
(a) Increase or augmentation in bulk; protuberance.
(b) Increase in height; elevation; rise.
Little River affords navigation during a swell
to within three miles of the Miami. --Jefferson.
(c) Increase of force, intensity, or volume of sound.
Music arose with its voluptuous swell. --Byron.
(d) Increase of power in style, or of rhetorical force.
The swell and subsidence of his periods.
3. A gradual ascent, or rounded elevation, of land; as, an
extensive plain abounding with little swells.
4. A wave, or billow; especially, a succession of large
waves; the roll of the sea after a storm; as, a heavy
swell sets into the harbor.
Of the long waves that roll in yonder bay.
The gigantic swells and billows of the snow.
5. (Mus.) A gradual increase and decrease of the volume of
sound; the crescendo and diminuendo combined; -- generally
indicated by the sign.
6. A showy, dashing person; a dandy. [Slang]
Ground swell. See under Ground.
Organ swell (Mus.), a certain number of pipes inclosed in a
box, the uncovering of which by means of a pedal produces
Swell shark (Zool.), a small shark (Scyllium ventricosum)
of the west coast of North America, which takes in air
when caught, and swells up like a swellfish.