A spinster is an unmarried woman who is past the usual age for marrying and is considered unlikely to marry.
An 18-year-old single woman would not be considered a spinster in contemporary language, but a single, 40-year-old woman may be considered a spinster. Several dictionaries flag it as a derogatory term. (See Current use.) A synonymous, but more pejorative, term is Old Maid.
The Online Etymological Dictionary says of the word origin and history:
The Oxford American Dictionary discussion of the word's etymology that "spinster" took on its meaning of a never-married woman in the early 18th century: "Origin late Middle English (in the sense 'woman who spins'): from the verb spin + -ster; in early use the term was appended to names of women to denote their occupation. The current sense dates from the early 18th century."
The term originally identified girls and women who spun wool, long before the Industrial Age. In medieval times, this was one of the few livelihoods available to a woman to bring in wages to contribute to the household's income or to live independently of a male wage. "Spinster" also evolved into a legal term to describe an unmarried female, commonly heard in the banns of marriage of the Church of England when the prospective bride is formally described as a "spinster of this parish".
(Jett-Hanna)
Maybe I don't wanna maybe I don't wanna, wanna
Maybe I don't wanna **** you!
I'm a spinster, I don't need no rules
I don't got no one tellin' me what to do
Tellin' me what's cool? I'm no stupid fool
Hey teen ageist I'm not over yet
Y-O-U-T-H only, baby, that's your math
I'm a spinster, I don't need your rules
I'm resisting, I don't need no one to
Tell me what's cool or how I need a tool
To get thru to you
I'm no one's wife and' I'm not your little girl
Don't tell me I'm useless cuz I want
More from this world
Maybe I don't wanna maybe I don't wanna, wanna
Maybe I don't wanna maybe I don't wanna
Maybe I don't wanna maybe I don't wanna, wanna
Maybe she don't wanna **** you!