early has 6 distinct synonyms spread across 4 of its 9 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 2 recorded opposites are middle, late.
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.
being or occurring at an early stage of development
“in an early stage”
before the usual time or the time expected
“she graduated early”
in good time
“he awoke betimes that morning”
2 of the 9 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for early.
Synonyms, antonyms and the broader and narrower relations for early come from Princeton University’s WordNet. Full sources and licences.