Definition of unfavourite in English:

unfavourite

(US unfavorite)

adjective

informal
  • [attributive] Least favourite; most disliked:

    ‘she was the unfavourite one of her mother's three children’
    • ‘A huge crowd queued excitedly for the opportunity to slap some foam on their favourite (or unfavourite) teacher.’
    • ‘He's always been one of my most unfavourite actors ever; this just makes it official.’

Pronunciation:

unfavourite

/ʌnˈfeɪv(ə)rɪt/