Meaning
What does TERF mean?
TERF is an acronym for the phrase “Trans-Exclusionary Radical Feminist”.
This is a minority movement of feminism, in which the members are advocating to the denial of women’s right or downright any voting rights for transgender women.
The members of the “TERF” movement are stating that only born women should have women’s rights.
Origin
What's the origin of TERF?
The term is accredited to the born female radical feminist Viv Smythe, who popularized the term in 2008, as an abbreviation for Trans-Exclusionary Radical Feminism.
Since then most of the feminists had embraced the expression, however the majority of Trans-Exclusionary Radical Feminists are not identifying with the term, because it had been often associated with hatred and violence.
Spread & Usage
How did TERF spread?
There are more or less radical members of the “TERF” movement, with some accounts of violence occurring toward transgender women.
During the 2010’s several public figures had been accused of being a “TERF”, the latest case being the famous author J.K. Rowling, because her tweets were seen as anti-trans.
Urban Dictionary has a number of various entries on the subject: https://www.urbandictionary.com/define.php?term=TERF

External resources
- Forbes – J.K. Rowling Comes Out As A TERF