alliance
1.
2. A connection based on kinship, marriage, or common interest; a bond or tie: the shifting alliances within a large family.
3. Close similarity in nature or type; affinity: the ancient alliance between mathematics and music.
4. The act of becoming allied or the condition of being allied: the church, acting in alliance with community groups.
[Middle English, from Old French aliance, from alier, to ally. See