[di.am.e.ter] n [ME diametre, fr. MF, fr. L diametros, fr. Gk, fr. dia- + metron measure--more at measure] (14c) 1: a chord passing through the center of a figure or body
2: the length of a straight line through the center of an object
3: a unit of magnification for an optical instrument equal to the number of times the linear dimensions of an object are apparently increased "a microscope magnifying 60 ~s" -- di.am.e.tral adj