Combination n. 1.The act or process of combining or uniting persons and things. "Making new compounds by new combinations." "A solemn combination shall be made Of our dear souls."
2.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. "A combination of the most powerful men in Rome who had conspired my ruin."
3.(Chem.) 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.
4.pl. (Math.) The different arrangements of a number of objects, as letters, into groups. Note: In combinations no regard is paid to the order in which the objects are arranged in each group, while in variations and permutations this order is respected.
Combination car, a railroad car containing two or more compartments used for different purposes. (U. S.)
Combination lock, a lock in which the mechanism is controlled by means of a movable dial (sometimes by several dials or rings) inscribed with letters or other characters. The bolt of the lock can not be operated until after the dial has been so turned as to combine the characters in a certain order or succession.
Combination room, in the University of Cambridge, Eng., a room into which the fellows withdraw after dinner, for wine, dessert, and conversation.
Combination by volume (Chem.), the act, process, or ratio by which gaseous elements and compounds unite in definite proportions by volume to form distinct compounds.
Combination by weight (Chem.), the act, process, or ratio, in which substances unite in proportions by weight, relatively fixed and exact, to form distinct compounds. See Law of definite proportions, under Definite. Synonyms: Cabal; alliance; association; league; union; confederacy; coalition; conspiracy. See Cabal. 
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