whacker

noun4

1. •
   One who, or something which, whacks.

   • Joe was just about the best Australian heavyweight at the time, a very tough customer in his own right. He didn't have any science, but he was a mighty whacker. — 1963
2. •
   (informal) Synonym of whopper (“anything large”).
3. •
   (informal) Synonym of whopper (“an outrageous or blatant lie”).
4. •
   (slang) A radio amateur who is keenly interested in emergency response and may travel to the sites of emergencies.