What is "consuetude"

Consuetude \Con"sue*tude\ (?; 144), n. [L. consuetudo. See Custom.] Custom, habit; usage. [R.]

To observe this consuetude or law.
--Barnes .

late 14c., from Middle French consuetude, from Latin consuetudo, from consuetus, past participle of consuescere "to accustom" (see custom).

n. custom, familiarity.

n. a custom or usage that has acquired the force of law