The definition is from the dictionary. I didn’t realise that book was in dispute as well? The story of the Oxford English Dictionary is fascinating and I highly recommend it — if only because it supports part of what you say.
But, your argument is weakened and perhaps dismissed by the construct of communication. If we can’t agree on the definition of words, we are surely doomed. We would never be really talking to each other.
The actions people take under the cover of words, perverting their original meaning, is another matter entirely. The Islam meme you quote is really an honest attempt by millions to remind islamaphobics that Islam is a religion, like Christianity, and can be used for good or evil.
Authoritarianism? I don’t think an attempt to clarify classifies my approach as such.