bĭpĕda

I. a tile or flagstone two feet long, for pavements (several times in Pall., elsewh. very rare), Pall. 1, 19, 1; 1, 40, 2 and 5; id. Mai, 11, 2 (twice); Inscr. Fabr. p. 511, 159 (cf. Vitr. 7, 1 fin.: tegulae bipedales).