source: Another Religious Post or: Hell, Why Not? | Fantasy and Anime

relating to or believing in a religion:

比較なし 〖名詞の前で〗宗教の, 宗教に関する〈物･事〉

e.g. both men were deeply religious, intelligent, and moralistic

e.g. religious music.

(of a belief or practice) forming part of someone's thought about or worship of a divine being:

〈人が〉信仰心の強い, 敬虔（けいけん）な(↔ irreligious)

e.g. he has strong religious convictions.

belonging or relating to a monastic order or other group of people who are united by their practice of religion:

比較なし 〖名詞の前で〗修道(会)の.

e.g. religious houses were built on ancient pagan sites.

treated or regarded with a devotion and scrupulousness appropriate to worship:

｟かたく｠ 〖通例名詞の前で〗良心的な; 細心の, 厳正な〈注意など〉

e.g. I have a religious aversion to reading manuals.

noun (plural same)

a person bound by monastic vows.

修道士, 修道女

religiousness |rəˈlijəsnəs| noun

Middle English: from Old French, from Latin religiosus, from religio ‘reverence, obligation’ (see religion).