-ess

from The Century Dictionary.

• noun The name of the letter S, s. It is rarely so written, the symbol S, s, being used in its stead.
• noun A large worm: so called from its often assuming the shape of an S.
• noun 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.

from the GNU version of the Collaborative International Dictionary of English.

• A suffix used to form feminine nouns.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• suffix Suffix appended to words to make a female form.