a. rare1. [f. EX- pref.1 + FOCAL.] Not passing through the focus.
1881. T. Stevenson, in Nature, XXIII. 560. The ex-focal rays proceeding from the outer edges of the flame.
a. rare1. [f. EX- pref.1 + FOCAL.] Not passing through the focus.
1881. T. Stevenson, in Nature, XXIII. 560. The ex-focal rays proceeding from the outer edges of the flame.