In English there are no masculine or feminine forms. English uses gender specific nouns for male or female.
The noun for a male who provides professional massages is masseur.
The noun for a female who provides professional massages is masseuse.
It should be noted that these terms are being replaced by the compound noun massage therapist, a common gender noun, a word for a male or a female who provides professional massages.
Masseur is masculine, masseuse is feminine.
The masculine form of the word meaning a person who massages the human body is masseur and the feminine form of the word is masseuse.
Masseuse
masseuse
The male form of masseuse is masseur.
That is the correct spelling of "masseuse" (feminine form of masseur, a massager).
The feminine form of alumnus is alumna. The feminine plural is alumnae.
The feminine form of bajo is baja. The feminine plural is bajas.
The feminine form of ami is amie. The feminine plural is amies.
Mistress is the feminine form of master. It is already in feminine form.
The feminine form of a baron is a baroness.
The feminine form of charmant is charmante. The feminine plural is charmantes.