Definition of whacker in English:

whacker

(also wacker)

noun

  • 1A person or thing that strikes something forcefully.

    • ‘It's more fun to ski from your bumper than hike a rocky trail in the dark, wondering when you'll finally get those branch whackers off your back and on to your feet.’
    • ‘That at least is the word from the ‘Nuevo Dia Newspaper’ which as all good Pinata whackers know means New Day.’
    • ‘Four inches of surface and a finger-grooved linen Micarta grip make this one upscale whacker.’
  • 2Australian informal A person who is stupid or annoying (used as a general term of abuse)

    ‘don't humour this guy, he's a whacker’
    • ‘He was ordered to withdraw a description of an opponent as a "whacker".’
    • ‘What are they doing now, the whackers?’
    • ‘It would ease his mind if all those whackers were dead.’
    • ‘Who else belongs to this mysterious group of celebrity whackers?’
    • ‘I can't imagine how they dared break the rules, with all those regulatory whackers waiting to pounce.’

Origin

Early 19th century (in sense ‘a heavy blow’): from whack + -er. Sense 2 is a back formation from wacky.

Pronunciation

whacker

/ˈwakə/