Is there an opposite to everything we know?

The "opposites" listed in the OP are subjective. The belief that any genuine opposites exist, and more significantly, that they "should" exist, is an artifact of a desire to find symmetry in a cosmos notorious for completely failing to be balanced or symmetrical.

I don't merely think by asserting a negative makes something it's opposite, Up is not the negation of down. Nor East the negation of West, if I traveled east on earth sooner or later I would wind up at my original starting place.

To say that the sun doesn't rise in the east is not the negation of saying the sun rises in the east, because in truth the sun doesn't rise at all.

what about idioms? When I say something is bad " man that's person bad " I'm giving the word a positive spin.

What if a person has a deterministic view of exist? I guess i'ts opposite couldn't exist meaning a person would believe there isn't such thing as free will.
After all, your question is phrased "Is there an opposite to everything we know?

What would be the opposite of "A cannot be true and false at the same time?

How can anyone not appreciate the usefulness of Fresco's contributions to these discussions?

[quote]Opposite of the color grey would probably be subjective to the individual based on perception.[/quote]

Isn't Gray the bastard child of Black and White?
Black being the absence of color and white being the Presence of color making Gray their interracial mixed child.

Also, I know football, that doesn't mean handball is it's opposite.
Tea is not the opposite of coffee, nor is solid the opposite of liquid because there're other states of matter like gases.

Thank you for that.
But as we both know this is hardly a specialist philosophy forum. It tends to be populated by interested "laymen" who tend to wander round the foothills of philosophical questions rather than put in the required efforts to climb to higher vantage points described in the literature. For example, the concept of the OP itself as an example of a speech act (Searle)* divorced from a specific real life context (childrens' classroom etc) and thereby leaving it open to "a free-for-all two cents worth", is unlikely to occur.

* (Note however that Searle clashed with many including Derrida so the term "assertion" rather than "speech act" may be preferable.)