Definition of jarhead in English:

jarhead

noun

US
informal
  • A US Marine.

    • ‘After all, how could some jarhead Marine know more about any subject than the Washington Post?’
    • ‘The entire manner in which the heavily criticized Patriot Act was passed into law is enough to give even the most jingoistic jarhead reason to pause.’
    • ‘I know what I meant, jarhead, I don't need the likes of you questioning my command of the language.’
    • ‘A lot is made in many movies of the physical training and the technical training that they experience in boot camp but I really think boot camp is to turn you into a jarhead.’

Origin

Early 20th century (originally US dialect, in the sense ‘mule’): from jar + head. The word originally referred to members of the US army, on account of the mule mascot of the Army football teams.

Pronunciation

jarhead

/ˈjärˌhed/