na-adjective
formal; courteous; ritualistic
Describes actions or attitudes that follow established forms or ceremonies, often with an implication of lacking genuine feeling or being merely perfunctory.
彼の謝罪は儀礼的で、心がこもっていなかった。
His apology was formal and lacked sincerity.
儀礼的な挨拶を交わした後、本題
After exchanging ritualistic greetings, we got down to business.
礼儀正しい means 'polite' or 'well-mannered' as a positive trait, whereas 儀礼的 can imply a more formal, sometimes hollow, politeness.
Compound of 儀礼 (ぎれい, 'ceremony, etiquette') + 的 (てき, '-like, -al'). The word 儀礼 itself is a Sino-Japanese term combining 儀 (ぎ, 'ceremony, rite') and 礼 (れい, 'propriety, thanks').