Lacerta \La*cer"ta\, n. [L. a lizard. See {Lizard}.] 1. (Zo["o]l.) A genus of lizards. See {Lizard}. Note: Formerly it included nearly all the known lizards. It is now restricted to certain diurnal Old World species, like the green lizard ({Lacerta viridis}) and the sand lizard ({L. agilis}), of Europe. 2. (Astron.) The Lizard, a northern constellation.