Lewis & Short

grădārĭus, a, um, adj. [gradus], of or belonging to steps, going or proceeding step by step (very rare; not in Cic.).

  1. I. Lit.: equus gradarius, a pacer, ambler, Lucil. ap. Non. 17, 25: pugna, Diom. p. 473 P.
  2. II. Trop., of a deliberate speaker: Cicero quoque noster gradarius fuit, Sen. Ep. 40, 11.