Stuart Hall’s definition of ideology, the working one in cultural studies:

By ideology I mean the mental frameworks—the languages, the concepts, categories, imagery of thought, and the systems of representation—which different classes and social groups deploy in order to make sense of, figure out and render intelligible the way society works.

Neither Marxist nor pejorative: ideology as the frameworks every group uses to make sense of the world, not a synonym for false belief. Which is what I mean by everything is ideology, though I admit Hall doesn’t say everything but rather everything about society. But this isn’t Hall’s website is it.