A1[C or U]the period of time someone has been alive or something has existed: Do you know the age of that building?What age (= how old)is your brother?I'd guess she's about my age (= she is about as old as I am).She was 74 years of age when she wrote her first novel.He left home at the age of 16.I was married with four children at your age.She's starting to show/look her age (= to look as old as she is).I'm really beginning to feel my age (= feel old).His girlfriend's twice his age (= twice as old as he is).Describing age and birthdaysact your age!›said to someone to tell them to stop behaving like someone who is much youngerExpressions telling people to stop doing somethingthe age of consent›the age at which someone is considered by the law to be old enough to agree to have sex with someoneStages of life