lif ‧ er /ˈlaɪfə $ -ər/ BrE AmE noun [countable]
[ Word Family: noun : ↑ life , ↑ lifelessness , ↑ lifer ; adjective : ↑ lifeless , ↑ lifelike , ↑ lifelong ; adverb : ↑ lifelessly ]
informal someone who has been sent to prison for the rest of their life