consuetudinous

adjective2

1. •
   Of or pertaining to consuetude; of an unwritten law established by usage, derived by immemorial custom from antiquity.

   • Sensual man, so attached to externals, etches the letter on his memory, clings fast to the consuetudinous, and cannot disengage himself from his delusive conceits. — 1838
2. •
   consuetudinary