From Longman Dictionary of Contemporary EnglishX chromosomeX chro‧mo‧some /ˈeks ˌkrəʊməsəʊm $ -ˌkroʊməsoʊm/ noun [countable]HBM a type of chromosome that exists in pairs in female cells, and together with a Y chromosome in male cells
Examples from the Corpus
X chromosome• In heterozygous females, pre-B cells whose active X chromosome expresses the mutant gene would not terminally differentiate and proliferate.• Consequently, a Cain gene on an X chromosome can safety kill the Y chromosome and not risk suicide.• Females may be variably affected by virtue of random inactivation of the X chromosome.• The pattern arises, we now know, because the gene is carried on the X chromosome.• It is carried on the X chromosome.• The gene is found on the X chromosome, males being more severely affected than females. 