[at.a.vism] n [F atavisme, fr. L atavus ancestor, fr. at- (prob. akin to atta daddy) + avus grandfather--more at uncle] (1833) 1 a: recurrence in an organism of a trait or character typical of an ancestral form and usu. due to genetic recombination b: recurrence of or reversion to a past style, manner, outlook, or approach "architectural ~"
2: one that manifests atavism: throwback -- at.a.vis.tic adj -- at.a.vis.ti.cal.ly adv