(1):

(v. t.) To fix the paternity of; - said of an illegitimate child; as, to affiliate the child to (or on or upon) one man rather than another.

(2):

(v. t.) To connect in the way of descent; to trace origin to.

(3):

(v. t.) To attach (to) or unite (with); to receive into a society as a member, and initiate into its mysteries, plans, etc.; - followed by to or with.

(4):

(v. i.) To connect or associate one's self; - followed by with; as, they affiliate with no party.

(5):

(v. t.) To adopt; to receive into a family as a son; hence, to bring or receive into close connection; to ally.