empty has 8 distinct synonyms spread across 5 of its 10 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 fill, full.
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.
holding or containing nothing
“an empty glass”
a container that has been emptied
“return all empties to the store”
1 of the 10 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for empty.
Synonyms, antonyms and the broader and narrower relations for empty come from Princeton University’s WordNet. Full sources and licences.