Definition of mossback in US English:

mossback

noun

North American
informal
  • An old-fashioned or extremely conservative person.

    • ‘But if we look for the reasons for his fall only in the sins of the mossbacks in Washington, we will miss an important part of the lesson of all of this.’
    • ‘I thought that I was a ‘mossback’, but the LA Weekly's Doug Harvey has now convinced me that I am a crackpot!’
    • ‘It won't really appease either the die-hard mossbacks or the fanatic up-to-the-minutes.’

Pronunciation

mossback

/ˈmɔsbæk//ˈmôsbak/