Demonstrâtor, tôris, m. g. pen. prod. Verbale. Colum. Cic.One that sheweth or declareth.
Lewis and Short: Latin dictionary
dēmonstrātor, ōris, m. [id.], one who points out or indicates; an indicator, exhibiter (very rare): uniuscujusque sepeliendi, Cic. de Or. 2, 86, 353: hujus rationis, Col. 3, 10, 20: medicinarum Aesculapius, Tert. Apol. 23.