radian
1 synonym for radian, grouped by meaning and by how common each one is.
Noun — In the International System of Units, the derived unit of plane angle, equal to the angle at the centre of a circle formed by an arc as long as the radius.
How to use radian
The word patterns that sound natural to a native speaker.
measured in radians
convert to radians
radians per second
angle in radians
It belongs to formal mathematical and scientific writing rather than everyday conversation.
Etymology
The word is formed from radius with the suffix -an added to it, reflecting how the unit is defined directly from a circle's radius.
Full origin of radian →Frequently asked questions
What is a radian in simple terms?
It is the unit for measuring angles based on the radius of a circle: one radian is the angle made at the centre when the arc length equals the radius.
What is the symbol for radian?
The unit can be written using the symbol rad, or sometimes the superscript c.
How is a radian different from a degree?
Both measure angles, but a radian is defined from the circle's own radius and arc length, while a degree divides a circle into 360 equal parts; the two units are used side by side depending on context.
