The word 'cleavage' has a few different meanings depending on the context in which it's used. In general, it refers to the act of splitting or dividing. In a more specific context, it can describe the separation between two portions of something, like the way a woman's breasts come together and create a visible line or gap. Additionally, 'cleavage' can refer to the division of the earth's crust into two layers or the distinctive separation of parts in various scientific fields, particularly in biology and geology.
The term 'cleavage' comes from the Middle English word 'clevage', which is derived from the verb 'cleave', meaning to split or divide. The roots can be traced back to Old English 'cleofian', which means to split or break.