Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prae-dŏcĕo, cŭi, ctum, 2, v. a., to teach, instruct, inform beforehand (very rare): illi praedocti a duce arma mutaverant, Sall. J. 94, 1: praedoctus esto, Plin. 18, 34, 77, § 334: myrrheus Pulvis sepulcrum praedocet, points out, shows, Prud. Cath. 12, 72.