ranger has 4 distinct synonyms spread across 3 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
a member of the Texas state highway patrol; formerly a mounted lawman who maintained order on the frontier
an official who is responsible for managing and protecting an area of forest
Synonyms, antonyms and the broader and narrower relations for ranger come from Princeton University’s WordNet. Full sources and licences.
a member of a military unit trained as shock troops for hit-and-run raids