臭 means 'foul-smelling'

These four kanji are practically symbiotic. The verb 嗅ぐ takes 香り, 臭い, and 匂い as direct objects. Although people usually reserve 臭い for stenches and 匂い for fragrances, these words (both におい) can be interchangeable. Each could convey that something "smacks of" a quality. Whereas 臭い can mean that a man looks suspicious, as if he "smells of" a crime, 嗅 enables people to sniff out crimes! Three of the kanji have ties to religion, and with 香 as "incense," that connection is strong.