nastiness, nauseate, sickening
噁 centers on a visceral reaction of disgust: something nasty that makes you feel sick or nauseated.
噁 combines 口 (mouth) with 惡 (bad, evil), suggesting a mouth-related reaction to something bad or disgusting. The exact historical development is uncertain.
The mouth radical 口 beside 惡 (evil/bad) paints a picture: your mouth reacts to something evil or bad with a sickened, nauseated feeling.
For オ, imagine an awful smell so nasty it makes you say 'Oh!' in disgust: Oh -> オ, and your mouth 口 reacts to the evil 惡 stench.
chirp; tweet; caw