In Bulgarian, the word "PROLET" actually means "spring." Its origin is rooted in old words commonly used among the people.

It is believed that the usage of the word in the sense of "spring" derives from ancient concepts in colloquial language. Additionally, due to regional dialect variations and linguistic changes that developed among people, the word has gained different meanings over time. Therefore, the Bulgarian word "PROLET" is used as a term that conveys a seasonal meaning, rather than its association with the concept of a social class, originating from much older colloquial speech.