fed·er·ate 
(fĕdə-rāt′)
(fĕdə-rāt′)v. fed·er·at·ed, fed·er·at·ing, fed·er·ates
v.tr.
To cause to join into a league, federal union, or similar association.
v.intr.
To become united into a federal union.
adj. (fĕdər-ĭt, fĕdrĭt)
United in a federation.
[Latin foederāre, foederāt-, to ratify an agreement, from foedus, foeder-, league, treaty; see bheidh- in the Appendix of Indo-European roots.]