-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
ancestress (s) (noun), ancestresses (pl)
A woman from whom a person is descended.
auditress
A female hearer or listener.
aviatress
A woman aviator.
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.