reservation has 5 distinct synonyms spread across 4 of its 7 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
a district that is reserved for particular purpose
a statement that limits or restricts some claim
“he recommended her without any reservations”
Synonyms, antonyms and the broader and narrower relations for reservation come from Princeton University’s WordNet. Full sources and licences.
an unstated doubt that prevents you from accepting something wholeheartedly
the act of reserving (a place or passage) or engaging the services of (a person or group)
“wondered who had made the booking”
the written record or promise of an arrangement by which accommodations are secured in advance
something reserved in advance (as a hotel accommodation or a seat on a plane etc.)
the act of keeping back or setting aside for some future occasion