A combination is a group of things put together, or the act of putting them together. When you create a combination, you're joining different elements into one unit or mixture.

Think about a combination lock: you need to turn the dial to specific numbers in sequence, and only that particular combination will open it. Or consider a combination pizza, which brings together multiple toppings like pepperoni, mushrooms, and peppers on one pizza. When a basketball player uses a combination of speed and skill, she's blending different abilities to play well.

The word appears everywhere: a scientist might discover a winning combination of ingredients for a new medicine, or a student might find that a combination of reading and practicing problems helps them learn best. In mathematics, combinations refer to the different ways you can select items from a group when the order doesn't matter (unlike permutations, where order does matter).

Sometimes people use “in combination with” to describe things working together. A recipe might call for baking soda in combination with vinegar to create a chemical reaction. The power of combination lies in how separate things can create something new or more effective when united.