mask of pregnancy vs melasma

mask of pregnancy and melasma both are nouns.

Word	Noun	Adjective	Verb	Adverb
mask of pregnancy	Yes	No	No	No
melasma	Yes	No	No	No

As nouns, mask of pregnancy and melasma are synonyms defined as:

mask of pregnancy and melasma: a tan discoloration of a woman's face that is associated with pregnancy or with the use of oral contraceptives

Other synonyms of mask of pregnancy include chloasma.

mask of pregnancy (noun)	melasma (noun)
a tan discoloration of a woman's face that is associated with pregnancy or with the use of oral contraceptives	a tan discoloration of a woman's face that is associated with pregnancy or with the use of oral contraceptives