Crumb \Crumb\, v. t. [imp. & p. p. {Crumbed} (kr[u^]md); p. pr. & vb. n. {Crumbing} (kr[u^]m"[i^]ng).] To break into crumbs or small pieces with the fingers; as, to crumb bread. [Written also {crum}.] [1913 Webster]