cautious has 2 distinct synonyms spread across 2 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is incautious.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
showing careful forethought
“reserved and cautious; never making swift decisions”
people who are fearful and cautious
“whitewater rafting is not for the timid”
Synonyms, antonyms and the broader and narrower relations for cautious come from Princeton University’s WordNet. Full sources and licences.