hydrophobic has 1 distinct synonym 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. Its one recorded opposite is hydrophilic.
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.
lacking affinity for water; tending to repel and not absorb water; tending not to dissolve in or mix with or be wetted by water
abnormally afraid of water
Synonyms, antonyms and the broader and narrower relations for hydrophobic come from Princeton University’s WordNet. Full sources and licences.