Question

what is a junk an define it

Answer 1

the junk mean the bakery food we eat and out side oil food the out side foods are called junk food

Answer 2

junk is a useless object.it is not of any cost anymore.
it is very old usually .
we call some eatables as junk food because it is of no use to our health.
we even call people as junk because they may not serve well for us.
but more often we call any useless objects as junk materials.

hope it helps!!!