Definition of rah in US English:

rah

exclamation

North American
  • A cheer of encouragement or approval.

    ‘“Yea! Rah! Team!”’
    • ‘The official beginning of cheerleading was in the 1920s when ivy-league schools had cheerleaders with coloured pompoms leading the crowd in choruses of, ‘rah, rah, sis, boom, bah!’’
    • ‘It was originally going to be Rachel with the room to herself, but now this, so yay rah!’
    • ‘‘Go, team, rah, rah, rah,’ Billie said, unenthusiastically.’
    • ‘Hayden stood up and gave a fake ‘rah, rah,’ doing his best male cheerleader impression.’

Origin

Late 19th century: shortening of hurrah.

Pronunciation

rah

/rɑ//rä/