di·am·e·ter
(di-ami-tər)
(di-ami-tər)n.
1. Abbr. d or diam.Mathematics
a. A straight line segment passing through the center of a figure, especially of a circle or sphere, and terminating at the periphery.
b. The length of such a segment.
2. Thickness or width.
3. A unit of magnification equal to the number of times an object's linear dimensions is increased by the magnifying apparatus.
[Middle Englishdiametre, fromOld French, fromLatindiametrus, fromGreekdiametros (gramme), diagonal (line) : dia-, dia- + metron, measure; see me-2 in the Appendix of Indo-European roots.]
di·ame·tral(-trəl)adj.
diameter