overage has 3 distinct synonyms spread across 1 of its 2 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 surplus or excess of money or merchandise that is actually on hand and that exceeds expectations
too old to be useful
“He left the house...for the support of twelve superannuated wool carders”
Synonyms, antonyms and the broader and narrower relations for overage come from Princeton University’s WordNet. Full sources and licences.