-ess

(Greek -issa > Late Latin -issa > Old French -esse > Middle English -esse: a suffix that forms nouns meaning a female +++, as in lioness, tigress, heiress, hostess, and sculptress)

When -ess is added to a noun ending in -tor, -ter, the vowel before r is generally elided (eliminated or left out), as in actress (actor + -ess); and such a derivative with the ending -tress (often equivalent to French ) is usually considered a reduced form of Latin -trix, -tricem and popularly regarded as the equivalent of -tor + -ess.

In Middle English many words in -esse were adopted from French; such as, countess, duchess, mistress, and princess, or formed on nouns in -er; such as, enchantress and sorceress.

—Based on information presented in
The Barnhart Dictionary of Etymology, Robert K. Barnhart, Editor;
The H.W. Wilson Company; Bronxville, New York; 1988; page 343.

The suffix -ess is diminishing from English usage, with trends or tendencies toward avoiding any unnecessary references to gender or sexual categorizing (feminine or masculine.

The suffixes -er and -or are no longer gender-specific in modern English: an author or manager, like a doctor or writer, may be male or female, so the words authoress and manageress are considered redundant.

Some -ess words remain in use; for example, heiress and actress, although actor is being used more often now for both men and women.

actress (s) (noun), actresses (pl)
1. A woman, or girl, who acts in plays, movies, or television.
2. A woman or girl who pretends to be someone else or to feel something so as to impress or to deceive someone or other people.
adulteress (s) (noun), adulteresses (pl)
A woman who commits immoral relations with a man who is not her husband.
adventuress (s) (noun), adventuresses (pl)
1. A woman who looks for dangerous undertakings: Sally's neighbor was an adventuress who wanted lots of money and be socially accepted, and therefore pursued daring exploits or by using her charm and by scheming to get what she wanted.
2. A woman of questionable reputation or character who seeks personal advancement; demirep: Mary knew of a woman who aimed for personal advancement in her job by means of sexual activity with her boss.
3. A female varietist: There was a rumour going around in the neighbourhood that one of the wives was an adventuress who had sexual relationships with other men, and not only with her husband!
ancestress (s) (noun), ancestresses (pl)
A woman from whom a person is descended.
auditress (s) (noun), auditresses (pl)
A female hearer or listener: The lecturer was aware that the people in the audience were also well- known auditresses and weren't to be forgotten in his preface before speaking.
aviatress (s) (noun), aviatresses (pl)
A woman who is a pilot and flies airplanes.
benefactress (s) (noun), benefactresses (pl)
A woman, or women, who are inclined to participate in activities which support individuals or institutions: Mrs. Humboldt, the primary benefactress for the children's hospital, often visited the patients and took gifts to them.
conductress
A woman who leads or directs; a woman conductor.
contendress
countess
1. The wife, or widow, of a count or earl.
2. A woman who holds the rank of count or earl.
creatress
She who creates.

A reference to a female who creates something.

crown princess
deaconess
demigoddess (s) (noun), demigoddesses (pl)
1. An important or greatly respected woman who is treated like a goddess.
2. A mythological being who is half woman and half goddess.
3. A female being, often the offspring of a god and a mortal, who has some but not all of the powers of a goddess.
duchess
The wife or widow of a duke.