Lewis & Short

admŏnĭtor, ōris, m. [admoneo].

  1. I. He that reminds or admonishes one of something, a monitor: misi ad te quattuor admonitores non nimis verecundos. Cic. Fam. 9, 8; so id. Top. 1 fin.
  2. II. One that urges to action, an admonisher (cf. admoneo, II. C.): admonitorque operum caelo clarissimus alto Luclfer ortus erat, Ov. M. 4, 664: admonitor praecepti, Cod. Th. 8, 8, 7.