Lewis & Short

contrā-pōno,

  1. I. no perf., pŏsĭtum, 3, v. a., to place opposite, to oppose to (several times in Quint.; elsewh. only in late Lat., and rare): non semper quod adversum est contraponitur, Quint. 9, 3, 84; Tert. ad Mart. 4.
  2. II. P. a. as subst.: contrā-pŏ-sĭtum, i, n., antithesis, Quint. 9, 3, 32; 9, 3, 81; 9, 3, 102 al.