someone, especially a child or young person, who is mature behaves in a sensible and reasonable way, as you would expect an adult to behave [≠ immature]:
Laura is very mature for her age.
We're mature enough to disagree on this issue but still respect each other.
fully grown and developed:
Mature apple trees are typically 20 feet tall.
The new leader wants his country to be seen as a mature democracy.
The human brain isn't fully mature until about age 25.
Most girls are sexually mature by about 14 years of age.
mature cheese, wine etc has a good strong taste which has developed during a long period of time:
wine/cheese etcDFDFD British English
a polite or humorous way of describing someone who is no longer young [= middle-aged]:
wedding fashions for mature brides
a respectable gentleman of mature years.
a mature piece of work by a writer or an artist is done late in their life and shows a high level of understanding or skill:
His mature work reveals a deep sense of enjoyment of nature.
after thinking carefully and sensibly about something for a long time:
On mature reflection we have decided to decline their offer.
a mature bond or policy is ready to be paid
a mature industry or market is one where growth is quite low and there are fewer competitors than before
If you want us to treat you as an adult, you have to act maturely.