X chromosome

Meaning

Noun

• A mammalian sex chromosome. Cells of females have a pair of X chromosomes while cells of males have an X and a Y.

Origin

• Named by Hermann Henking in 1890 from x (signifying the unknown) due to some baffling properties he had observed. The brief resemblance in the appearance of the X and Y chromosomes to the letters "X" and "Y" respectively during cell division is entirely coincidental.