- a sex chromosome of humans and most mammals that determines femaleness when paired with another X chromosome and that occurs singly in males.
Compare Y chromosome.
Origin of X chromosome
First recorded in 1910–15
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- the sex chromosome that occurs in pairs in the diploid cells of the females of many animals, including humans, and as one of a pair with the Y-chromosome in those of malesCompare Y-chromosome
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
- The sex chromosome associated with female characteristics, occurring paired in the female and singly in the male sex-chromosome pair.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- The sex chromosome that in female mammals is paired with another X-chromosome and in males is paired with a Y-chromosome. Very few genes on the X-chromosome have counterparts on the Y-chromosome, and since males have only one X-chromosome, any gene present on it (even if the gene is recessive in females) is expressed in males. In females, one of the two X-chromosomes in each cell is deactivated. See more at sex chromosome. See note at sex.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.