n. & v.
n. 1 attention to safety; prudence, carefulness. 2 a esp. Brit. a warning, esp. a formal one in law. b a formal warning and reprimand. 3 colloq. an amusing or surprising person or thing.
v.tr. 1 (often foll. by against, or to + infin.) warn or admonish. 2 esp. Brit. issue a caution to. caution money Brit. a sum deposited as security for good conduct.
[ ME f. OF f. L cautio -onis f. cavere caut- take heed ]