af·fil·i·ate • v. / əˈfilēˌāt/ [tr.] (usu. be affiliated with) officially attach or connect (a subsidiary group or a person) to an organization: the college is affiliated with the University of Wisconsin. ∎  [intr.] officially join or become attached to an organization: the membership of the National Writers Union voted to affiliate with the United Auto Workers.• n. / -it/ a person or organization officially attached to a larger body.DERIVATIVES: af·fil·i·a·tive / -ətiv; -ˌātiv/ adj.

affiliate XVIII. f. pp. stem of medL. affiliāre, f. AF- + filius son (see FILIAL); prob. after F. affilier; see -ATE3.
So affiliation XVIII. — F. — medL.