adversarial(characteristic of, or in the manner of, an adversary) adjective [UK: ˌæd.və.ˈseə.riəl] [US: ˌæd.vər.ˈse.riəl]
adverse(unfavourable) adjective [UK: ˈæd.vɜːs] [US: æd.ˈvɝːs]If you wouldn't like a person of a different race, would you be adverse to a friendly alien? = Si no quisieras a una persona de una raza diferente, ¿serías adverso a un extraterrestre amistoso?
untoward(unfavourable, adverse, or disadvantageous) adjective [UK: ˌʌn.tə.ˈwɔːd] [US: ən.tuː.ˈɔːrd]