- Temperature scale (also called Centigrade) with 0°C at the freezing point of pure water and 100°C at its boiling point at standard atmospheric pressure at sea level on the Earth
- noun a scale for measuring temperature in which water freezes at 0° and boils at 100°.
- noun a metric scale of temperature on which 0° is the point at which water freezes and 100° is the point at which water boils under average atmospheric conditions.
- adjective a scale of temperatures where the freezing and boiling points of water are 0° and 100°
Origin & History of “Celsius”
The notion of a temperature scale based on 100 was developed by the Swedish astronomer Anders Celsius (1701–1744) (he originally had water boiling at zero and freezing at 100º, but this was later reversed). His name began to be used to designate the scale in English around the middle of the 19th century. In popular parlance it has usually taken a back seat to centigrade (a French invention, first recorded in English in 1812), but it remains the preferred term in scientific usage.