Flash, subst. 1) a burst of light, a sudden blaze: “lightning f.” Tit. II, 1, 3. Caes. I, 3, 52. Per. III, 1, 6. Cymb. IV, 2, 270.
2) a sudden burst or outbreak of high spirits: “the f. and outbreak of a fiery mind,” Hml. II, 1, 33. “your --es of merriment,” V, 1, 210.