Combination

1. The act or process of uniting by chemical affinity, by which substances unite with each other in definite proportions by weight to form distinct compounds.
2. The act or process of combining or uniting persons and things.
3. The different arrangements of a number of objects, as letters, into groups.
4. The result of combining or uniting; union of persons or things; esp. a union or alliance of persons or states to effect some purpose; -- usually in a bad sense.