An archaic or rare variant adjective meaning 'relating to knowledge or epistemology,' essentially equivalent to 'epistemic' or 'epistemological.'
A now-obsolete adjectival form derived from Greek 'episteme' (knowledge), possibly representing an earlier attempt to create the adjective before 'epistemic' became standard in modern philosophy.
Words like 'epistemonical' show that English speakers in the 1600s-1700s were still experimenting with how to talk about knowledge philosophically—the winners of those experiments are the ones we use today.
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