vapour
Meaning
A mass of tiny drops of liquid in the air, for example steam
A substance in a form like gas, often one that can be seen as a mist or fog
Usage
A cloud is a mass of water vapour in the sky.
The cold glass was covered in a film of vapour from her breath.
The chemical reaction produced a toxic vapour.
Etymology
The word 'vapour' entered English in the late 14th century from Anglo-French 'vapour', which itself came from Latin 'vapor' meaning 'steam, exhalation, heat'. The Latin term is of uncertain deeper origin but may be connected to the concept of exhaling or blowing. The core semantic journey is from the physical phenomenon of steam or warm exhalation observed in nature to the modern scientific and general term for a visible mist or a substance in a gaseous state. This evolution reflects a continuity of the core idea of a diffused, airborne substance.
Analysis
The word 'vapour' is a simplex loanword from Anglo-French and Latin. It does not contain separable, meaningful morphemes within its modern English spelling.