From Longman Dictionary of Contemporary Englishthe chance/experience etc of a lifetimethe chance/experience etc of a lifetimeBESTthe best opportunity, experience etc that you will ever have It was the holiday of a lifetime. → lifetime
Examples from the Corpus
the chance/experience etc of a lifetime• There is also the chance of a lifetime for the talented teams who win through to the final.• We are offering the experience of a lifetime, and it seems to appeal to people from all over the world.• Jim assured him that hearing me sing was the experience of a lifetime, but Dad wasn't having that.• This was the chance of a lifetime. 