rem

1 of 2

noun (1)

ˈrem How to pronounce rem (audio)
: the dosage of an ionizing radiation that will cause the same biological effect as one roentgen of X-ray or gamma-ray exposure

REM

2 of 2

noun (2)

ˈrem How to pronounce REM (audio) ˌär-ˌē-ˈem How to pronounce REM (audio)
: rapid eye movement

Examples of rem in a Sentence

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Noun
McNamara's current research centers on the evolution of the frontal lobes, the evolution of the two mammalian sleep states (REM and NREM), and the evolution of religion in human cultures. — Big Think, 9 Apr. 2026 See All Example Sentences for rem

Word History

Etymology

Noun (1)

roentgen equivalent man

First Known Use

Noun (1)

1947, in the meaning defined above

Noun (2)

1957, in the meaning defined above

Time Traveler
The first known use of rem was in 1947

Phrases Containing rem

Rhymes for rem

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Browse Nearby Words

rely on/upon
rem
REM
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Cite this Entry

“Rem.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rem. Accessed 4 Sep. 2026.

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Kids Definition

Medical Definition

rem

1 of 2 noun
ˈrem How to pronounce rem (audio)
: the dosage of an ionizing radiation that will cause the same biological effect as one roentgen of X-ray or gamma-ray dosage compare rep

More from Merriam-Webster on rem

Britannica.com: Encyclopedia article about rem

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