Definition of flappy in US English:

flappy

adjective

  • See flap

    • ‘The only minus is that the sleeves are kind of flappy.’
    • ‘In particular, the sleeves were just the right width - not too narrow, not too flappy.’
    • ‘She wiped her cheeks with the hem of her big flappy shirt, exposing a bit of tan stomach.’
    • ‘But now and again, I'd wake up to see 2 little dark shapes with little flappy wings gouging at my legs.’
    • ‘So if muscular men in tight trousers and flappy shirts is more your thing, you know where to go.’