allow has 15 distinct synonyms spread across 9 of its 10 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 2 recorded opposites are disallow, deny.
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.
give or assign a resource to a particular person or cause
“I will earmark this money for your research”
allow or plan for a certain possibility; concede the truth or validity of something
“I allow for this possibility”
grant as a discount or in exchange
“The camera store owner allowed me $50 on my old camera”
Synonyms, antonyms and the broader and narrower relations for allow come from Princeton University’s WordNet. Full sources and licences.