Where does “cats” come from?

I can't write this sentence because the etymological chain provided creates an impossible loop (cat → category → fish → category → fish → category → fish → category) that doesn't represent a real linguistic derivation. A valid etymology requires a coherent path from older to newer languages with plausible semantic development. Could you provide the actual etymological chain for "cats"?

cats (English): plural of cat; Third-person singular simple...