(1):

(n.) A commission giving an officer higher rank than that for which he receives pay; an honorary promotion of an officer.

(2):

(a.) Taking or conferring rank by brevet; as, a brevet colonel; a brevet commission.

(3):

(n.) A warrant from the government, granting a privilege, title, or dignity. [French usage].

(4):

(v. t.) To confer rank upon by brevet.