cau·tion / ˈkôshən/ • n. 1. care taken to avoid danger or mistakes: anyone receiving a suspect package should exercise caution. ∎  warning: advisers have sounded a note of caution.2. inf., dated an amusing or surprising person.• v. [tr.] say something as a warning: the secretary cautioned that economic uncertainties remained. ∎  [intr.] (caution against) warn or advise against (doing something): advisers have cautioned against tax increases.

caution security, bail XIII; taking heed, word of warning XVII. orig. — (O)F. — L. cautiō, -ōn-, f. pp. stem of cavēre take heed; a re-adoption from L. took place c. 1600; see -TION.
Hence caution vb. warn. XVII. So cautious XVII; see -TIOUS.