mycosisPronunciation: /mʌɪˈkəʊsɪs/Definition of mycosis noun (plural mycoses /-siːz/) a disease caused by infection with a fungus, such as ringworm or thrush. Derivatives mycoticPronunciation: /-ˈkɒtɪk/ adjective mycosis in other Oxford dictionaries Definition of mycosis in the US English dictionary