a-riot,advb.phr.|əˈraɪət| [a prep.1 + riot.] In riot, riotously, running riot. 1851M. Howitt Sk.Nat.Hist. (ed. 7) 14 Till the Parrots, all a-riot, Chattered too to keep you quiet.1881Cornh. Mag. Mar. 310 The rose-trees..have gone wandering a-riot into country hedges.