femininize
/ˈfɛmɪnɪnʌɪz/(also femininise)
verb
1 [with object] To give a feminine form to (a word); to make (a word) feminine. Frequently in pass. Now rare.
2 [with object] To make feminine in nature or character; = feminize.
Origin
Late 18th century; earliest use found in Samuel Pegge (1733–1800), antiquary and writer. From feminine + -ize.