His teachers have complained about his 'immature' behavior.
The flock included both adult and 'immature' birds.
The fruit was still 'immature'. [='unripe']
(..) - Yeah. - And that woman was your... - Friend. I'll just get a paper. So... ...do you date immature men? Almost exclusively. I have no letters. Ma, will you go already? - What are you doing? - I just want to see something. (..)1990 TvShow: Seinfeld Title: The Stakeout Season: 1 Episode 2