(1):

(n.) A horse for riding or driving; a nag; a pony.

(2):

(n.) A horse or pony kept for hire.

(3):

(n.) A hired drudge; a hireling; a prostitute.

(4):

(v. t.) To carry in a hackney coach.

(5):

(v. t.) To devote to common or frequent use, as a horse or carriage; to wear out in common service; to make trite or commonplace; as, a hackneyed metaphor or quotation.

(6):

(a.) Let out for hire; devoted to common use; hence, much used; trite; mean; as, hackney coaches; hackney authors.

(7):

(n.) A carriage kept for hire; a hack; a hackney coach.