offensive smell; stench; foul odor
Refers to an unusual, unpleasant smell, often implying something is wrong or suspicious. Used in both literal and figurative contexts.
台所から異臭がする。
There's a strange smell coming from the kitchen.
事件の背
I sense something fishy behind the incident.
異臭 means an unusual or strange smell that is not necessarily unpleasant, whereas 悪臭 specifically means a foul, offensive smell.
Compound of 異 (い, 'different, unusual') and 臭 (しゅう, 'smell, odor'). The reading しゅう is the on'yomi of 臭.