na-adjective, noun
bad manners; rudeness
Refers to behavior that is impolite or lacking in proper etiquette. Can be used as a noun or adjectival noun (e.g., 不行儀な).
彼の不行儀な態度に皆が驚いた。
Everyone was surprised by his rude behavior.
食事中の不行儀は避けるべきだ。
You should avoid bad manners during meals.
不作法 also means bad manners, but 不行儀 can sound slightly more formal or old-fashioned.
Compound of 不 (fu, 'not') and 行儀 (gyōgi, 'manners, etiquette'). The exact historical derivation is uncertain, but the word has been used since at least the Edo period.