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: any of one or more genetically determined antigens present in the red blood cells of most persons and of higher animals and capable of inducing intense immunogenic reactions
Word History
Etymology
rhesus monkey (in which it was first detected)
First Known Use
1942, in the meaning defined above
Dictionary Entries Near Rh factor
Cite this Entry
“Rh factor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Rh%20factor. Accessed 5 Nov. 2024.
Kids Definition
Rh factor
noun
: a protein on the red blood cells of some people that is one of the substances used to classify human blood as to compatibility for transfusion and that when present in a fetus but not the mother causes a serious condition in which the mother produces antibodies that cross the placenta and attack the red blood cells of the fetus
Etymology
from rhesus monkey, the animal in which the Rh factor was found
Medical Definition
Rh factor
noun
: a genetically determined protein on the red blood cells of some people that is one of the substances used to classify human blood as to compatibility for transfusion and that when present in a fetus but not in the mother causes a serious immunogenic reaction in which the mother produces antibodies that cross the placenta and attack the red blood cells of the fetus
called also rhesus factor
More from Merriam-Webster on Rh factor
Britannica.com: Encyclopedia article about Rh factor
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