Definition from Wiktionary, the free dictionary
combination (plural combinations)
- The act of combining, the state of being combined or the result of combining.
- A sequence of numbers or letters used to open a combination lock.
- (mathematics) One or more elements selected from a set without regard to the order of selection.
- An association or alliance of people for some common purpose.
- (billiards) A combination shot; a billiard; a shot where the cue ball hits a ball that strikes another ball on the table.
Derived terms 
Related terms 
act of combining
sequence of numbers or letters for a combination lock
one or more elements selected without regard of the order