aid has 10 distinct synonyms spread across 6 of its 6 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 person or thing that is a resource that helps make something easier or possible to do
“visual aids in teaching”
the activity of contributing to the fulfillment of a need or furtherance of an effort or purpose
“he gave me an assist with the housework”
gift of money or other material help to support a person or cause
“economic assistance to depressed areas”
the work of providing treatment for or attending to someone or something
“no medical care was required”
improve the condition of
“These pills will help the patient”
Synonyms, antonyms and the broader and narrower relations for aid come from Princeton University’s WordNet. Full sources and licences.