ally (a nation united to another by treaty or league)

to cooperate

cooperation; working together

union; alliance

to ally

solution, settlement / (music) Progression from dissonance to consonance; a chord to which such progression is made; resolution

(transitive) solve, resolve, settle (a problem, a trouble, a criminal case) / (intransitive) be solved, be settled / (intransitive) can be solved; be soluble

a land, a large place / a country in general, a region / a country as in a nation, a state / the office of emperor, the crown; affairs of state / a province of ancient Japan

question, problem on homework etc. / a question; a matter (of time etc.) / a problem (something that needs to be dealt with); a trouble / an issue; a matter

(chiefly women's speech) first person singular pronoun: I, me