Merriam-Webster says:
demure
de·mure
di-ˈmyu̇r
Synonyms of demure
1
: reserved,
modest
2
: affectedly modest, reserved, or serious
: coy
demurely adverb
demureness noun
Did you know?
In the nearly seven centuries that
demure has been in use, its meaning has only shifted slightly. While it began solely as a descriptive term for people of quiet modesty and sedate reserve—those who don't draw attention to themselves, whether because of a shy nature or determined self-control—it came to be applied also to those whose modesty and reservation is more
affectation than sincere expression. While
demure sounds French and entered the language at a time when the native tongue of England was borrowing many French words from the
Normans, the etymological evidence requires that we exercise restraint: the word's origin remains obscure.