Why would I use a unique definition? The purpose of language is communication, so I stick to common definitions whenever I can. In this case, I mean the same thing that other socialists mean when they talk about people who put social identity above class.

I wrote more about identitarianism here: https://medium.com/a-universalist-in-an-identitarian-age/the-political-cube-the-political-compass-plus-universalism-vs-identitarianism-9d40d2f0ec2d