hopeless 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 hopeful.
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.
without hope because there seems to be no possibility of comfort or success
“in an agony of hopeless grief”
3 of the 4 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 hopeless.
Synonyms, antonyms and the broader and narrower relations for hopeless come from Princeton University’s WordNet. Full sources and licences.