Definition from Wiktionary, the free dictionary
-ess (plural -esses)
- Suffix appended to words to make a female form.
Usage notes 
- Professions ending in -ter or -tor change to -tr when this suffix is added.
- This suffix tends to be regarded as sexist and as such is starting to fall into disuse; a single, gender-neutral term is preferred by many even though it is a less specific term.
- Glenda Jackson is a famous actor.
- Glenda Jackson is a famous actress. More specific language signaling that Glenda is a female.
- Depending on etymology, other feminine affixes are used; see synonyms.
Derived terms 
- “-ess” in Douglas Harper, Online Etymology Dictionary (2001).