over-the-hill
UK[ˌəʊvə ðə ˈhɪl]US[ˌoʊvər ðə ˈhɪl]
adj
(informal) No longer young, in good health, or effective in one's job; past one's prime.
Etymology
The phrase "over the hill" originates from the literal image of climbing a hill, where the peak represents the prime of life. The journey "over the hill" metaphorically signifies having passed that peak and being on the downward, declining slope. This analogy, equating life's trajectory with a physical journey, became a common euphemism for aging in mid-20th century American English. Its informal, often humorous tone softens the direct reference to decline, encapsulating the concept of being past one's best in a vivid, pictorial idiom.
Analysis
This is a fixed idiomatic phrase. It is not productively formed from separable morphemes for the purpose of this analysis. Its meaning is derived from the metaphorical interpretation of the entire phrase.
Examples
He joked that at forty, he was officially over-the-hill.
The coach was accused of being over-the-hill and out of touch with modern tactics.
She refused to accept the over-the-hill label and started a successful new business.