'weather-glass' originates from English, a compound of 'weather' and 'glass', where 'weather' (Old English 'weder') referred to atmospheric conditions and 'glass' (Old English 'glæs') referred to a glass vessel or item made of glass.

'weather-glass' appeared in English usage from the late 17th to early 18th century; earlier and variant spellings include 'weather glass' and 'weatherglass', all referring to a glass instrument used to observe changes in the weather (i.e., a barometer).

Initially it meant 'a glass vessel used in instruments for observing atmospheric changes'; over time it narrowed to mean specifically 'a barometer' or 'an instrument used to predict the weather.'