Dictionary.com
definitions

Rh factor

[ ahr-eych fak-ter ]
/ ˈɑrˈeɪtʃ ˌfæk tər /

noun Physiology.

any of a type of specific antigen present on the surface of red blood cells, persons having inherited such antigens being designated Rh+ (Rh positive) and persons lacking them, a much smaller group, being designated Rh− (Rh negative): blood of Rh− persons is incompatible with Rh+ blood because of antibody reaction, and an Rh− woman who bears an Rh+ baby will have formed antibodies to the fetal blood that, unless removed from her bloodstream by apheresis in a subsequent pregnancy, will be carried across the placenta and destroy red blood cells of the next Rh+ fetus, resulting in erythroblastosis in the newborn.

RELATED CONTENT

Offbeat Literary Genres To Get Lost InRead more in this article about some frequently asked questions and fun facts related to our definitions.
READ MORE
Woof, Blaf, Or Voff? How Animals Speak Across The WorldRead more in this article about some frequently asked questions and fun facts related to our definitions.
READ MORE

RELATED WORDS

Rh-negative, Rh-positive, antigen

Origin of Rh factor

First recorded in 1940–45; so called because first found in the blood of rhesus monkeys
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for rh factor

Rh factor

noun

an agglutinogen commonly found in human blood: it may cause a haemolytic reaction, esp during pregnancy or following transfusion of blood that does not contain this agglutinogenFull name: rhesus factor See also Rh positive, Rh negative

Word Origin for Rh factor

C20: named after the rhesus monkey, in which it was first discovered
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for rh factor

Rh factor

1942, from the first letters of rhesus; so called because the blood group, and its effects, were discovered in the blood of rhesus monkeys (1941).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for rh factor

Rh factor

n.

Any of several substances on the surface of red blood cells that induce a strong antigenic response in individuals lacking the substance.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for rh factor

Rh factor

[ är′āch′ ]

Any of several antigens present on the surface of red blood cells in most humans. People with Rh factors are classified as having a blood type that is Rh positive, while people who lack the antigen are said to be Rh negative and can produce powerful antibodies that destroy red blood cells if given a blood transfusion from an Rh-positive donor. A woman who is Rh negative and is pregnant with an Rh-positive fetus can produce antibodies that are life threatening to the fetus. See Note at blood type.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Culture definitions for rh factor

Rh factor

[ (ahr-aych) ]

Any of several substances found on the surface of red blood cells in persons.

Note

An Rh-negative woman who gives birth to an Rh-positive baby may develop antibodies to the Rh factor during her first pregnancy. These antibodies may cause a disorder in Rh-positive babies conceived afterward that could result in the death of the infant if the condition is not recognized and treated.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.