A trainer is someone who teaches specific skills or helps others improve at something, usually through practice and coaching. A personal trainer at a gym shows people how to exercise safely and effectively. A dog trainer teaches dogs to follow commands and behave well. Companies hire trainers to teach employees how to use new computer systems or work more efficiently.

The word emphasizes hands-on teaching rather than just lecturing. While a teacher might explain math concepts in a classroom, a trainer works directly with you, watching your technique, correcting mistakes, and helping you practice until you get it right. An animal trainer spends hours working with each animal, building trust and teaching specific behaviors through repetition and rewards.

Athletes also use the word differently: their trainer is the person who treats injuries and keeps them physically healthy, more like a specialized medical professional than a coach.

In Britain and some other countries, trainers also means athletic shoes or sneakers, the kind you wear for sports or running around. So a British kid might ask their trainer (coach) to tie their trainers (shoes) before practice! In American English, we usually just call them sneakers or athletic shoes.