The word 毕生 is a disyllabic compound formed by combining two morphemes: 毕 (bì), which means "to finish" or "to complete", and 生 (shēng), which means "life". Together, they create a metaphorical meaning through semantic fusion, where 毕 ("end/completion") modifies 生 ("life") to express the concept of "from the beginning to the end of a lifetime". Thus, the word literally translates to "the whole life" or "all one's life", functioning as an adverb or adjective to describe something lasting a lifetime.