Lewis & Short

1. cernŭus, a, um, adj. [root kar, v. celsus; cf. κάρηνον, cerebrum],

  1. I. with the face turned towards the earth, inclined forwards, stooping or bowing forwards (very rare and only poet.): cernuus dicitur proprie inclinatus, quasi quod terram cernit, Non. p. 20, 33 sq.; Lucil. ib. p. 21, 1: ejectoque incumbit cernuus armo, * Verg. A. 10, 894 (v. Serv. ad h. 1.): cernuus inflexo sonipes effuderat armo, Sil. 10, 255 sq.; Arn. 7, p. 246.
  2. II. That turns a somersault; a tumbler, mountebank, κυβιστητήρ, πεταυριστής, Lucil. ap. Non. p. 21, 6; Varr. ap. Serv. ad Verg. A. 10, 894; cf. Gloss. Philox.: cernuli πεταυρισταί.