noun

1. The state of being allied.

   “matrimonial alliances; an alliance between church and state, or between two countries”

2. The act of allying or uniting.

3. A union or connection of interests between families, states, parties, etc., especially between families by marriage and states by compact, treaty, or league.

Synonyms: union, coalition, confederation, league, team, affinity, allyship, connection

verb

1. To connect or unite by alliance; to ally.