This is the opportunity 'of a lifetime'. = This sort of opportunity comes along 'once in a lifetime'. [=this is a very rare opportunity]
a baseball player's 'lifetime' batting average [=batting average measured over a baseball player's full career]
She was presented with a 'lifetime' achievement award. [=an award for all the work she has done in her life]
(..) to have a silver smile? What did he say? He said mercury salts. For what purpose? He said, "One night with Venus, a lifetime of Mercury." Thank you. You know there's people gossiping, you with that girl. Just because she didn't grow up in a shtetl (..)2018 TvShow: The Alienist Title: These Bloody Thoughts Season: 1 Episode 4