Rh-negative

adjective

Rh-neg·a·tive ˌär-ˌāch-ˈne-gə-tiv

: lacking Rh factor in the red blood cells

Word History

First Known Use

1945, in the meaning defined above

Time Traveler

The first known use of Rh-negative was in 1945

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rhm

Rh-negative

rho

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Cite this Entry

Style

“Rh-negative.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Rh-negative. Accessed 4 Feb. 2026.

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Kids Definition

Rh-negative

adjective

ˌär-ˌāch-

: lacking Rh factor on the red blood cells

Medical Definition

Rh-negative

adjective

Rh-neg·a·tive ˌär-ˌāch-ˈneg-ət-iv

: lacking Rh factor in the red blood cells

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