rad

UK: /ræd/ US: /ræd/ ,(rad)

WordReference Random House Learner's Dictionary of American English © 2026

rad¹ /ræd/   n. [countable] [Physics.]

1. Physics a unit of measure for a dose of radiation absorbed by the body.

rad² /ræd/  adj. [Slang.]

1. radical .

WordReference Random House Unabridged Dictionary of American English © 2026

rad¹  (rad), n. [Physics.]

1. Physics a unit of absorbed dose equal to 0.01 Gy. Cf. dose (def. 4a).

• shortened form of radiation 1915–20

rad²  (rad), n. 

1. [Informal.] radical.

adj. 

2. Slang Terms fine;
   wonderful.

• by shortening of radical

rad, [Math.]

1. Mathematics radian;
   radians.

rad., [Math.]

1. Mathematics radical.
2. Mathematics radix.

Collins Concise English Dictionary © HarperCollins Publishers::

rad / ræd/ noun

1. a former unit of absorbed ionizing radiation dose equivalent to an energy absorption per unit mass of 0.01 joule per kilogram of irradiated material. 1 rad is equivalent to 0.01 gray

Etymology: 20th Century: shortened from radiation

rad symbol

1. radian

Collins Concise English Dictionary © HarperCollins Publishers::

rad. abbreviation

1. radical
2. radius