-ess

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Female: lioness.

Century Dictionary and Cyclopedia

1. n. The name of the letter S, s. It is rarely so written, the symbol S, s, being used in its stead.
2. n. A large worm: so called from its often assuming the shape of an S.
3. n. A suffix theoretically attachable to any noun denoting an (originally masculine) agent, to form a noun denoting a female agent, as hostess, abbess, prioress, chieftainess, authoress, etc. It is most frequent with nouns in -er, as bakeress, breweress, Quakeress, etc. In such words as instructress, directress, editress, mistress, visitress, etc., the suffix is really -tress (see -tress), but in popular apprehension it is -ess added to the termination of the corresponding masculines, instructor, director, editor, mister (master), visitor, etc., such masculines being usually in pronunciation, and sometimes in spelling, assimilated to native English nouns in -er, as directer, instructer, visiter, etc., editor as if *editer, etc. In some cases the feminine form exists, while the masculine form is obsolete, as in governess (governor in a corresponding sense being obsolete); mistress, used in some senses without a corresponding use of mister or master.

Wiktionary

1. n. Suffix appended to words to make a female form.

GNU Webster's 1913

1. A suffix used to form feminine nouns.