The word 'terminus' is a direct borrowing from Latin, where it originally referred to a boundary stone or a limit. The Latin term itself is derived from the Proto-Indo-European root terə-, meaning 'to cross over, pass through, overcome', which conceptually relates to the idea of a boundary or a point that marks a transition. In ancient Roman religion, Terminus was the god who protected boundary markers, imbuing the word with a sense of sacred finality. This literal sense of a physical limit evolved into the modern abstract meanings of an endpoint, goal, or final station on a transportation line.

Structure: termin (boundary, end) + us (masculine noun suffix) - termin: From Latin terminus, meaning a boundary, limit, or end point. - us: A Latin masculine noun suffix used to form nouns from roots.