Old English nunne "woman devoted to religious life under vows of celibacy, poverty, and obedience to a superior," also "vestal, pagan priestess," from Late Latin nonna "nun, tutor," originally (along with masc. nonnus) a term of address to elderly persons, perhaps from children's speech, reminiscent of nana (compare Sanskrit nona, Persian nana "mother," Greek nanna "aunt," Serbo-Croatian nena "mother," Italian nonna, Welsh nain "grandmother;" see nanny).
"a nun, a religious woman," 1690s, from French religieuse, fem. of religieux "monk, religious person" (itself used in English from 1650s but much less common), noun use of the adjective meaning "religious" (see religious). As a type of pastry, attested from 1929.
"female singer of popular songs," 1866, from French chanteuse (16c.), fem. agent noun of chanter "to sing" (from PIE root *kan- "to sing"). In Old French, the word was chanteresse, which gave Middle English chaunteresse "nun who sings or leads the singing" (late 14c.). Milton has chauntress, but the word seems to have gone extinct before the 19c. reborrowing.
1670s, "a nun," from clergy + woman on the model of clergyman. Not seriously as "woman pastor, woman of the clerical profession" until 1871; in between it was used humorously for "old woman" or "domineering wife of a clergyman." Clergess as "member of a female religious order" is attested from late 14c.; clergy-feme as "clergyman's wife or woman" is attested from 1580s.