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• rem
  rem

  noun

  the quantity of ionizing radiation whose biological effect is equal to that produced by one roentgen of x-rays.
• REM
  REM

  noun

  rapid eye movement.

rem

¹ American  

[rem] / rɛm /

noun

Nucleonics.

1. the quantity of ionizing radiation whose biological effect is equal to that produced by one roentgen of x-rays.

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REM ² American  

[rem] / rɛm /

noun

1. rapid eye movement.

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REM ¹ British  

/ rɛm /

acronym

1. roentgen equivalent man

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REM ² British  

abbreviation

1. rapid eye movement

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rem Scientific  

/ rĕm /

1. The amount of ionizing radiation required to produce the same biological effect as one rad of high-penetration x-rays. The rem has been replaced in most scientific contexts by the sievert.

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rem Cultural  

1. An acronym for r oentgen e quivalent m an. A unit of absorbed doses of radiation.

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Discover More

A normal medical x-ray delivers about 0.02 rem; a fatal dose of radiation is several thousand rem.

Etymology

Origin of rem¹

1945–50; r(oentgen) e(quivalent in) m(an)

Origin of REM²

First recorded in 1955–60

Example Sentences

See Examples For:

rem REM

The legal limit for radiation exposure in the workplace is 5 rem per year.

From Slate ● Dec. 11, 2015

Multiply by 100 to obtain dose in rem.

From Textbooks ● Aug. 12, 2015

I would take 25 rem just to save my cat.

From Forbes ● May 19, 2013

According to the government report, with each scan, the average passenger receives a dose of about 1.46 microrems, or millionths of a rem, the standard measure of a person’s radiation exposure.

From Time ● Mar. 3, 2012

Argaven was now in seclusion in the summer-palace at Warrever, and had named Pemmer Harge rem ir Tibe as Regent during his confinement.

From "The Left Hand of Darkness" by Ursula K. Le Guin

A different pattern appeared as the brain moved from non-REM sleep into REM sleep.

From Science Daily ● Sep. 26, 2026

This northeast Georgia city has a rich music history, tied to bands including Widespread Panic, REM and The B-52s.

From MarketWatch ● Sep. 24, 2026

I scan to see how much deep sleep and REM I clocked.

From The Wall Street Journal ● Sep. 11, 2026

We live in an era of hyper-quantification, with the ability to track everything from the number of steps we walk in a day to our heart rate to the hours spent in REM sleep.

From Slate ● Aug. 29, 2026

Mom stands inside my room and annoyingly knocks on my door until I drag myself from REM dreams.

From "Ask the Passengers" by A.S. King