to warn or advise: The newspapers caution against overoptimism.
Origin: 1250–1300; Middle English caucion < Latin cautiōn- (stem of cautiō) a taking care, equivalent to caut(us), past participle of cavēre to guard against (cau- take care, guard + -tus past participle suffix) + -iōn--ion
c.1300, "bail, guarantee, pledge," from O.Fr., "security, surety," from L. cautionem (nom. cautio), from cautus pp. of cavere "to be on one's guard" (see caveat). The Latin sense re-emerged in Eng. 16c.-17c. The verb sense of "to warn" is from 1640s.