dog's age
An extremely long time
A dog's age is a very long time: I haven't seen her in a dog's age.
The expression likely plays on the idea that a year of human time equals seven dog years, making any span feel stretched out.
It's informal and folksy, most common in American English.
- yonksInformal British eternity
- donkey's yearsAn extremely long time
- eonsImmense spans of time
- foreverFor all time
- month of SundaysExtremely prolonged period
since forever · millennia · decades · centuries · lifespan · blue moon · eternity · long haul · healthspan · old as dirt · seniority · puppyhood · long time · maturity · light-years · time immemorial · longevity · aeons