(1):

(v. t.) To furnish or give experimental knowledge of; to make (one) to know; to make familiar; - followed by with.

(2):

(v. t.) To communicate notice to; to inform; to make cognizant; - followed by with (formerly, also, by of), or by that, introducing the intelligence; as, to acquaint a friend with the particulars of an act.

(3):

(v. t.) To familiarize; to accustom.

(4):

(v. t.) Acquainted.