'anti-cautious' is a modern English formation combining the prefix 'anti-' (from Greek 'anti-', meaning 'against') with the adjective 'cautious' (from Latin roots relating to being on guard).

'cautious' entered English via Old French 'cautieux' from Latin 'cautus' (past participle of 'cavēre', 'to be on guard'); the productive English prefix 'anti-' (from Greek 'anti') was later attached to form 'anti-cautious' as a descriptive compound in modern English.

The components originally meant 'against' and 'on guard'; combined in modern usage they yield the sense 'against being on guard' or 'opposed to caution', i.e., risk-taking or reckless behavior.