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.-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 illustration.-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.-a segment gear.-one of the cells or division formed by segmentation, as in egg cleavage or in fissiparous cell formation.-one of the divisions, rings, or joints into which many animal bodies are divided; a somite; a metamere; a somatome.-to divide or separate into parts in growth; to undergo segmentation, or cleavage, as in the segmentation of the ovum.