Lewis & Short

assentātor (ads-), ōris, m. [assentor], one who assents flatteringly, a flatterer (most freq. in Cic.).

  1. I. Lit.: semper auget adsentator id, quod is, cujus ad voluntatem loquitur, vult esse magnum, Cic. Lael. 26, 98: ita fit, ut is adsentatoribus patefaciat aures suas maxime, qui ipse sibi adsentetur et se maxime ipse delectet, id. ib. 26, 97; id. Off. 1, 14, 42; 1, 26, 91; 2, 18, 63; id. Caecin. 5, 14: Adsentatores jubet ad lucrum ire poëta Dives agris, * Hor. A. P. 420.
  2. II. Trop.: non auctor, sed adsentator mali, one who connives at, Tert. adv. Herm. 10.