leak has 8 distinct synonyms spread across 4 of its 9 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.
an accidental hole that allows something (fluid or light etc.) to enter or escape
“one of the tires developed a leak”
soft watery rot in fruits and vegetables caused by fungi
a euphemism for urination
“he had to take a leak”
unauthorized (especially deliberate) disclosure of confidential information
tell anonymously
“The news were leaked to the paper”
enter or escape as through a hole or crack or fissure
“Water leaked out of the can into the backpack”
have an opening that allows light or substances to enter or go out
“The container leaked gasoline”
Synonyms, antonyms and the broader and narrower relations for leak come from Princeton University’s WordNet. Full sources and licences.