Opisthocœlian

{ O‐pis′tho‐cœ″li‐an (?), O‐pis′tho‐cœ″lous (?), } a. [Gr. ὄπισθεν behind + κοι̑λοσ hollow,] (Anat.) Concave behind; — applied especially to vertebræ in which the anterior end of the centrum is convex and the posterior concave.