What is meant by the word "kharīf" (autumn) in the hadiths that mention units of measurement such as "seventy kharīfs" or "forty kharīfs"?

The meaning of "autumn" in the hadiths is (year), and it is an example of mentioning a part to signify the whole; because every year has one autumn, so if seventy autumns have passed, then seventy years have passed. This is a well-known Arabic idiom, like their saying: "I saw an 'ayn (eye)," meaning a spy. It was mentioned in Fath al-Bari that autumn is a known season of the year, and what is meant by it is the whole year. Its specific mention, rather than other seasons, is due to it being the purest of seasons, as fruits are harvested therein.