Semidiameter

[,semidai'æmitә]

Definition

(noun.) the apparent radius of a celestial body when viewed as a disc from the earth.

Inputed by Huntington--From WordNet

Definition

(n.) Half of a diameter; a right line, or the length of a right line, drawn from the center of a circle, a sphere, or other curved figure, to its circumference or periphery; a radius.

Inputed by Bennett