na-adjective
conventional; bound by custom
Describes attitudes, practices, or systems that adhere to established customs, often with a slightly negative nuance of being old-fashioned or resistant to change.
彼の考え方は因習的で、新しい提案を受け入れない。
His way of thinking is conventional and he won't accept new proposals.
Conventional customs still remain in that village.
慣習的 also means 'customary' or 'conventional', but is more neutral and focuses on habitual practice rather than the slightly negative, old-fashioned nuance of 因習的.
Formed from 因習 (convention, custom) + 的 (adjectival suffix). The exact historical derivation of 因習 is uncertain, but the kanji 因 (cause, reason) and 習 (learn, custom) suggest 'customs based on precedent'.