melasma

noun

1. a tan discoloration of a woman's face that is associated with pregnancy or with the use of oral contraceptives

   noun.state

   Synonyms chloasma mask of pregnancy

   Source: WordNet 3.0

2. A dark discoloration of the skin, usually local; as, Addison's <i>melasma</i>, or Addison's disease.

   noun

   Source: webster1913