serviceable has no recorded synonym. 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 one recorded opposite is unserviceable.
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.
ready for service or able to give long service
“serviceable equipment”
2 of the 3 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 serviceable.
Synonyms, antonyms and the broader and narrower relations for serviceable come from Princeton University’s WordNet. Full sources and licences.