'gas-off' originates from the English word 'gas,' which comes from the Greek word 'khaos,' meaning 'chaos' or 'void.' The term 'off' is used to indicate the action of releasing or emitting.

'gas' was adopted into English in the 17th century, and 'off' has been used in English since Old English times to indicate separation or removal.

Initially, 'gas' referred to any air-like substance, but over time it evolved to specifically mean a state of matter that expands freely to fill any space available.