14 letters · 20 points in Scrabble
noun a manual describing the customs of a particular group (especially the ceremonial practices of a monastic order)
originFrom Medieval Latin cōnsuetudinārius, from cōnsuētūdō (oblique stem cōnsuētūdin-) + -ārius, from cōnsuēscō + -tūdō, from con- + suēscō. By surface analysis, consuetude + -ary.
Etymology from Wiktionary, CC BY-SA 3.0