This is the “definition” (self identified) in all its badly written glory, punctuation and grammar as it appears on Dictionary.com:
TERF is used to describe cisgender women who self-identify as feminist but who are opposed to including transgender women in spaces they reserve for people who were assigned female at birth. This is because they believe trans women are men and since men cannot coexist with their feminist ideologies, they exclude them from their beliefs and support. In fact, they often believe they should be denied rights and sometimes advocate for harm against trans people
In use online since at least 2008, TERF has different connotations, depending on who is using it. Those who use it to describe others note that it’s descriptive in nature, and not insulting.
But, well-known feminists who have been labeled TERF on the internet have come out to call the term a slur, because it is associated with violence and hatred.
Never mind if I’m offended by the content or not, I’m offended on behalf of dictionaries and the English language that anyone is attempting to pass this off as a coherent definition of anything other than “this is what happens when women say no to misogynists”.