1) A British slang term for shoes; specifically running shoes or cross fit shoes.
2) A term used to describe an uglier women whom you are engaged in sexual relations with, but solely for the purpose of gaining experience.
1) "Oi mate! How you like my new trainers?" "Fookin' mint, mate!"
2)"Awh, man, she's a solid -10 though." "Yeah, but she's just a trainer."