noun

1. A fully grown human or animal.

2. A person who has reached the legal age of majority.

Synonyms: grown up

verb

1. To (cause to) be or become an adult.

2. To behave like an adult.

adjective

1. Fully grown.

   “an adult human, animal, or plant”

2. Intended for or restricted to adults rather than children.

   “adult clothes”

3. Containing material of an explicit sexual nature; of, or pertaining to, pornography.

   “This program contains adult content. Parental discretion is advised.”

Synonyms: X-rated, XXX, XXXX, pornographic, big, fully grown, grown up, grown up