a joining or merging of different parts or qualities in which the component elements are individually distinct.
a combination of blackberries, raspberries, and rhubarb
a sequence of numbers or letters used to open a combination lock.
a combination briefcase
a selection of a given number of elements from a larger number without regard to their arrangement.
His final publication was on combinations where he used the notation (m, n) for the combinations of n objects selected from m objects.