Federal  adj. 1 of a system of government in which self-governing states unite for certain functions etc. 2 of such a federation (federal laws). 3 of or favouring centralized government. 4 (federal) us of the northern states in the civil war. 5 comprising an association of largely independent units.  federalism n. Federalist n. Federalize v. (also -ise) (-zing or -sing). Federalization n. Federally adv. [latin foedus covenant]