1. Intimate union, or association of two or more persons or things, by set purpose or agreement, for effecting some object, by joint operation; in a good sense, when the object is laudable; in an ill sense, when it is illegal or iniquitous. It is sometimes equivalent to league, or to conspiracy. We say, a combination of men to overthrow government, or a combination to resist oppression.
2. An assemblage; union of particulars; as a combination of circumstances.
3. Commixture; union of bodies or qualities in a mass or compound; as, to make new compounds by new combinations.
4. Chimical union; union by affinity.
Mix dry acid of tartar with dry carbonate of potash; no combination will ensue, till water is added.
5. In mathematics, the union of numbers or quantities in every possible manner; or the variation or alteration of any number of quantities, letters, sounds, or the like, in all the different manners possible. The number of possible changes or combinations is found by multiplying the terms 18.104.22.168.5 continually into each other. Thus 1x2=2: 2x3=6: 6x4=24: 24x5=120. etc. So the permutations of five quantities amount to 120. The changes that may be rung on twelve bells amount to 479,001,600. And the twenty four letters of the alphabet admit of 62,044,840,173,323,943,936,000 changes or combinations.