ˈbär-, ˈbȧ(r- noun
Usage: usually capitalized 1st B
Etymology: after Murray Llewellyn Barr died 1995 Canadian anatomist
: a densely staining inactivated condensed X chromosome that is present in each somatic cell of most female mammals and is used as a test of genetic femaleness (as in a fetus or an athlete) — called also sex chromatin