reach has 30 distinct synonyms spread across 13 of its 13 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.
reach a point in time, or a certain state or level
“The thermometer hit 100 degrees”
be in or establish communication with
“Our advertisements reach millions”
the limits within which something can be effective
“range of motion”
an area in which something acts or operates or has power or control: "the range of a supersonic jet"
“a piano has a greater range than the human voice”
Synonyms, antonyms and the broader and narrower relations for reach come from Princeton University’s WordNet. Full sources and licences.