Semidiameter

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Semidiameter \Sem`i*di*am"e*ter\, n. (Math.)
     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.
     [1913 Webster]



From WordNet (r) 2.0 [wn]:

  semidiameter
       n : the apparent radius of a celestial body when viewed as a
           disc from the earth