chlo·as·ma 
(klō-ăzmə)
(klō-ăzmə)n. pl. chlo·as·ma·ta (-mə-tə)
A patchy brown or dark brown skin discoloration that usually occurs on a woman's face and may result from hormonal changes, as in pregnancy.
[New Latin, from Greek khloasma, greenness, from khloazein, to be green, from khloos, greenish color; see ghel-2 in the Appendix of Indo-European roots.]