n.
  - the length of time that a person or thing has existed. 
▸a particular stage in someone's life.
 ▸old age.
 - a distinct period of history. 
▸a division of geological time that is a subdivision of an epoch.
 ▸
(ages/an age)
 informal a very long time.
 
v.
 (ages, ageing or aging, aged)
 grow or cause to appear old or older. 
▸(with reference to an alcoholic drink, cheese, etc.) mature.
 
  Phrase
  
    - act 
(or be)
 one's age
 behave in a manner appropriate to someone of one's age.  - come of age
 reach adult status (in UK law at 18).  - of an age
  - old enough to be able or expected to do something.
 - (of two or more people or things) of a similar age.
 
 
   
  Derivative
  
    
      - ageing 
(also aging)
 n. & adj.
 
    
   
  Etymology
  ME: from OFr., based on L. aetas, aetat-, from aevum ‘age, era’.