customer

noun4

1. •
   a person or group that pays a business for the things or the work it provides

   • Every person who passes by is a potential customer.
   • Airlines are the chief customers of the commercial divisions of large-aircraft manufacturers such as Airbus, Boeing, and Embraer.
2. •
   (informal) A person, especially one engaging in some sort of interaction with others.

   • Pug could just see Slote's pale face under his fur hat. "I don't agree with you on that. He's a pretty tough customer, Hopkins." — 1971
3. •
   (India, historical) A native official who exacted customs duties.

   • His houses […] are seized on by the Customer. — 1609
4. •
   (no longer used) A habitual patron, regular purchaser, returning client; a person or company who has a custom of buying from a particular business.