A search on Dictionary.com turns up:
Part of Speech: n, adj
Definition: beyond one’s knowledge or province; pertaining to opinions given on matters beyond one’s knowledge; also written ultra-crepidarian
Etymology: from Latin ‘beyond the sole’
Ultracrepidarian comes from a classical allusion. The Latin writer Pliny recorded that Apelles, the famous Greek painter who was a contemporary of Alexander the Great, would put his pictures where the public could see them and then stand out of sight so he could listen to their comments. A shoemaker once faulted the painter for a sandal with one loop too few, which Apelles corrected. The shoemaker, emboldened by this acceptance of his views, then criticised the subject’s leg. To this Apelles is reported as replying (no doubt with expletives deleted) that the shoemaker should not judge beyond his sandals, in other words that critics should only comment on matters they know something about. In modern English, we might say “the cobbler should stick to his last”, a proverb that comes from the same incident. (A last is a shoemaker’s pattern, ultimately from a Germanic root meaning to follow a track, hence footstep.)
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