Seg"ment (?), n. [L. segmentum,
fr. secare to cut, cut off: cf. F. segment. See
Saw a cutting instrument.] 1. One of the
parts into which any body naturally separates or is divided; a part
divided or cut off; a section; a portion; as, a segment of an
orange; a segment of a compound or divided leaf.
2. (Geom.) A part cut off from a figure
by a line or plane; especially, that part of a circle contained
between a chord and an arc of that circle, or so much of the circle as
is cut off by the chord; as, the segment acb in the
3. (Mach.) (a) A piece
in the form of the sector of a circle, or part of a ring; as, the
segment of a sectional fly wheel or flywheel rim.
(b) A segment gear.
4. (Biol.) (a) One of
the cells or division formed by segmentation, as in egg cleavage or in
fissiparous cell formation. (b) One of the
divisions, rings, or joints into which many animal bodies are divided;
a somite; a metamere; a somatome.
Segment gear, a piece for receiving or
communicating reciprocating motion from or to a cogwheel, consisting
of a sector of a circular gear, or ring, having cogs on the periphery,
or face. -- Segment of a line, the part of
a line contained between two points on it. -- Segment of
a sphere, the part of a sphere cut off by a plane, or
included between two parallel planes. -- Ventral
segment. (Acoustics) See Loor,
Seg"ment (?), v. i. (Biol.)
To divide or separate into parts in growth; to undergo
segmentation, or cleavage, as in the segmentation of the