The word 'stem' originates from the Proto-Germanic stamniz, which referred to a tree trunk or a root. This, in turn, can be traced back to the Proto-Indo-European root stebh-, meaning 'to support, place firmly, or post'. The core concept of a central supporting structure is beautifully preserved throughout its evolution. From its literal botanical sense, the meaning broadened metaphorically to describe the slender supporting part of man-made objects like glasses. The verb sense, 'to stop the flow of', developed in the late 14th century, likely from the notion of damming up a stream at its source or stem.

This word is a simplex form. It is a direct descendant from the Old English 'stefn' or 'stemn', meaning the stem of a tree or the prow of a ship. Its functional role is as a base noun and verb.