ebb has 7 distinct synonyms spread across 3 of its 5 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 one recorded opposite is tide.
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.
Synonyms, antonyms and the broader and narrower relations for ebb come from Princeton University’s WordNet. Full sources and licences.
hem in fish with stakes and nets so as to prevent them from going back into the sea with the ebb
fall away or decline
“The patient's strength ebbed away”