consuetudinary

noun

1. A ritual book containing the forms and ceremonies used in the services of a particular monastery, cathedral or religious order.

   “Winchester itself was an early centre of the manufacture of chanlons, which were rugs used for coverlets or counterpanes, and in the consuetudinary of the city, which dates back at least to the early years of the thirteenth century, the looms are divided into two classes, the 'great looms' used for burel weaving paying 5s. per year, and the 'little looms' for chanlons paying 6d. or 12d., according to their size.”

2. An unwritten law established by usage, derived by immemorial custom from antiquity.

adj

1. (not-comparable)Customary; considered law by virtue of the fact that it is generally observed.