mucousPronunciation: /ˈmjuːkəs/Definition of mucous adjective relating to, producing, covered with, or of the nature of mucus. Derivatives mucosityPronunciation: /-ˈkɒsɪti/ noun Origin: mid 17th century: from Latin mucosus (see mucus)mucous in other Oxford dictionaries Definition of mucous in the US English dictionary