radian

Meaning

In the International System of Units, the derived unit of plane angular measure of angle equal to the angle subtended at the centre of a circle by an arc of its circumference equal in length to the radius of the circle. Symbol: rad.

Synonyms

rad

curvature

illuminant

light source

source

source of light

photosource

luminous source

optical source

radian measure

illuminating source

actinium

light source luminaire

Pronounced as (IPA)

/ˈɹeɪdiən/

Etymology

From radius + -an.