All the terms that acquired a different meaning over the last 5 years

• science
  • now it means "whatever authorities / journocels / celebrities tell you to believe", no matter how unscientific (according to the prior definition) it may be
• vaccine
  • Merriam-Webster changed the definition; we have covered the topic too
• anti-vax
  • we've written a solid article about that too
• racist
  • used to mean "odious discrimination against people solely based on race"
  • now it's some sort of evil original sin that, apparently, only white people are capable of, consisting (more or less) on not subordinating oneself to non-white people
• white supremacist
  • it used to mean "people who believe whites should be supreme"
  • now it just means "people who notice hatred against whites"
• safety
  • now it includes people who fear others saying obvious truths they disagree with
• man / woman
  • people with penises can be women now — people with vaginas can be men
• pregnant
  • the term would always imply woman before, nowadays "men can be pregnant too" (see prior definition)
• -phobic
  • used to mean "irrational fear"
  • now it simply acts as an insult, often proffered as revenge for making a joke or questioning a shibboleth
• violence
  • it now includes thoughts, written or said, that others hate and want to proscribe
• peaceful
  • conversely vis a vis the prior one, this now includes physically violent acts like arson, battery and attempted murder
•  healthy
  • morbidly obese people are "healthy", according to  "health at every size " activists
•  insurrection
  • peaceful protests / marches are called "insurrection" now
• misogyny
  • today it's used  in the sense of "disagreement with a woman" (or, more and more frequently, a man who incorrectly believes himself to be a woman)
• sexism
  • used to mean "irrational hatred of the other sex" or "odious discrimination against people solely based on sex"
  • today, it's an accusation of evil or sin, that may or may not be vaguely related to sex
  • in the modern definition, women are not capable of sexism — they can only be victims of it — so only men can be accused of sexism
• two weeks
  • it clearly means either "two years" or "for as long as we can get away with"
• far right
  • used to be reserved for organized violent groups animated by right-wing beliefs
  • today it generally means anyone to the left of, or slightly to the right of, Bill Clinton
• conspiracy theorist
  • someone who tells a truth that is generally accepted today, only six months early
• quarantine
  • formerly, forced isolation of sick people
  • now, forced isolation of even provably healthy people
• passport
  • now it includes permits to engage in ordinary everyday activities that were arbitrarily prohibited, rather than being limited to permits for international travel
• censorship
  • now it excludes censorious acts by businesses or individuals, even when those acts are clearly done at the behest of, or in accordance with the extralegal wishes of, a government
• hate speech
  • this one is a bit of a neologism
  • the term covers many categories of ideas, many of which are truthful, almost none of which are hateful (in the original sense), that certain people revile to see communicated 
• freedom of speech
  • before, the notion that you are free to communicate ideas, and other are free to listen to you, without fear of retaliation or interference by third parties
  • now, an obsolete practice that protects the communication of "hate speech"
• trust / safety
  • before, reliability and freedom from danger or injury
  • now, the name of a corporate department in charge of deforming or falsifying (often true) information the corporation intends to suppress, and censoring people communicating said information 
• fascist
  • before, a person who supports a government under fascistic principles
  • now, anyone who rejects certain left-wing ideas
• fact-checker
  • before, someone in charge of checking the truth value of factual claims
  • now, someone who routinely distorts or suppresses (often true) factual claims

How about others you might know?  Tell us!

In Newspeak it was seldom possible to follow a heretical thought further than the perception that it was heretical: beyond that point the necessary words were nonexistent.

— George Orwell, appendix: the principles of Newspeak