why do people help make old cars look bad

This is a highly offensive word and should be stricken from our modern vocabulary. Some people here have family or friends with mental disabilities and this is very insulting. Rani you're a good kid and I'm sure you meant no harm, but you're better than that.

Except that the "word" is still used for medical diagnosis and therapy plans.

Using as slang I can understand, but ask your child or family members' OT what the clinical chart says. If the diagnosis doesn't fit "typical" diagnosis such as Down's or Autism, it'll almost always say "retardation."