late 14c., necessite, "constraining power of circumstances; compulsion (physical or moral), the opposite of liberty; a condition requisite for the attainment of any purpose," from Old French necessité "need, necessity; privation, poverty; distress, torment; obligation, duty" (12c.), from Latin necessitatem (nominative necessitas) "compulsion, need for attention, unavoidableness, destiny," from necesse (see necessary). Meaning "condition of being in need, want of the means of living" in English is from late 14c.
Necessity is the Mother of Invention. [Richard Franck, c. 1624-1708, English author and angler, "Northern Memoirs," 1658]
To maken vertu of necessite is in Chaucer. Related: Necessities.
Old English -istre, from Proto-Germanic *-istrijon, feminine agent suffix used as the equivalent of masculine -ere (see -er (1)). Also used in Middle English to form nouns of action (meaning "a person who ...") without regard for gender.
The genderless agent noun use apparently was a broader application of the original feminine suffix, beginning in the north of England, but linguists disagree over whether this indicates female domination of weaving and baking trades, as represented in surnames such as Webster, Baxter, Brewster, etc. (though modern spinster probably carries an originally female ending).
Also compare whitester "one who bleaches cloth;" kempster (c. 1400; Halliwell has it as kembster) "woman who cleans wool." Chaucer ("Merchant's Tale") has chidester "an angry woman" (the 17c. had scoldster). Also compare Middle English shepster (late 14c.) "dressmaker, female cutter-out," literally "shapester." Sewster "seamstress" (Middle English seuestre, late 13c. as a surname, also used of men) is still in Jonson but was obsolete or provincial after 17c. In Modern English, the suffix has been productive in forming derivative nouns (gamester,roadster, punster, rodster "angler," etc.).