high season has 1 distinct synonym spread across 1 of its 1 sense. 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 off-season.
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.
the season when travel is most active and rates are highest
“they traveled to Europe in high season”
Synonyms, antonyms and the broader and narrower relations for high season come from Princeton University’s WordNet. Full sources and licences.