customers
"Customers" is a very common everyday word with a straightforward meaning, though it has a couple of useful shades of sense worth knowing.
A customer is someone who pays for something — a product or a service — from a business. Think of the people who walk into a shop, order food at a restaurant, or book a hotel room. All of them are customers. This is by far the most common meaning of the word.
everyday language, business · Modern, widely used
Sometimes people use 'customer' to describe a person by their personality or behavior — usually in a slightly humorous or cautious way. For example, a 'tough customer' means someone who is difficult to deal with or not easily pushed around. You will often see this in phrases rather than on its own.
everyday language · Modern, slightly informal · figurative