trainer

Etymology

train + -er

noun

1. A person who trains another; a coach.
   It was [Roger] Federer’s ability to pull him around the court that put the lactic acid and debilitating weight in those legs and he should not have been allowed the luxury of his trainer’s help. 29 June 2012, Kevin Mitchell, “Roger Federer back from Wimbledon 2012 brink to beat Julien Benneteau”, in The Guardian, archived from the original on 2016-11-15
2. (sports) A person responsible for treating injuries sustained by players during matches; a physiotherapist.
   He served Nelson wholeheartedly as a player, coach and trainer in a lengthy association, the highlights being his involvement in two championship-winning sides. 2009, Garth Dykes, Nelson FC in the Football League, page 22
3. (Britain) A running shoe or sneaker.
4. (video games, slang) A patch for a video game that applies cheats.
   I actually never got a trainer for RCT, but needed one for my brother when I installed it on his computer. He is 10, and is only concerned with making "cool" coasters. I also completed CF before getting trainers. 2000, Phil, “I need trainer for version 1.10.021”, in alt.games.rctycoon (Usenet)
   Are there any sites that have original copies of games? (ie: Summer/Winter/World Games with Fast Loading). Just looking for games without the trainers/intros. 2001, LJames4728, “Good C64 Game Sites?”, in alt.c64 (Usenet)
5. (cycling) A piece of indoor equipment allowing a bicycle to be ridden while stationary.
6. attributive form of trainers
   There was chewing gum stuck to my trainer soles.