rad Definition

rad¹
Rad
noun

1. politics.
Short for radical.

adj

(originally & especially N Amer)
1. slang
A shortened form of radical adj 9.

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rad²
noun

rad, rads
1. physics.
The unit formerly used to measure the amount of ionizing radiation absorbed, equal to 0.01 joule per kilogram of absorbing material, equivalent to 0.01 gray.

Etymology: 1950s: from radiation absorbed dose.

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rad³
abbreviation

1. Radian.

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radian
noun

1. geom.
The SI unit of plane angular measurement, approximately 57°, defined as the angle that is made at the centre of a circle by an arc (a segment of the circumference) whose length is equal to the radius of the circle.

Etymology: 19c: from radius.