The state of being allied; the act of allying or uniting; a union or connection of interests between families, states, parties, etc., especially between families by marriage and states by compact, treaty, or league; as, matrimonial alliances; an alliance between church and state; an alliance between France and England.
- A close association of nations or other groups, formed to advance common interests or causes: an alliance of labor unions opposing the bill.
- A formal agreement establishing such an association, especially an international treaty of friendship.
- A connection based on kinship, marriage, or common interest; a bond or tie: the shifting alliances within a large family.
- Close similarity in nature or type; affinity: the ancient alliance between mathematics and music.
- The act of becoming allied or the condition of being allied: the church, acting in alliance with community groups.