1. the length of a straight line passing through the center of a circle and connecting two points on the circumference (Freq. 27) • Syn: diam • Derivationally related forms: diametral, diametric, diametrical • Hypernyms: length • Hyponyms: bore, gauge, caliber, calibre, windage • Part Meronyms: radius, r 2. a straight line connecting the center of a circle with two points on its perimeter (or the center of a sphere with two points on its surface)(Freq. 1) • Derivationally related forms: diametral, diametric, diametrical • Hypernyms: straight line