WordNet records no synonym and no antonym for age of consent. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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 minimum age for marrying without parental consent or the minimum age for consensual sexual relations; intercourse at an earlier age can result in a charge of assault or statutory rape; the age differs in different states of the Union
Synonyms, antonyms and the broader and narrower relations for age of consent come from Princeton University’s WordNet. Full sources and licences.