fibrosisPronunciation: /fʌɪˈbrəʊsɪs/Definition of fibrosis noun [mass noun] Medicine the thickening and scarring of connective tissue, usually as a result of injury. Derivatives fibroticPronunciation: /-ˈbrɒtɪk/ adjective Origin: late 19th century: from Latin fibra (see fibre) + -osisfibrosis in other Oxford dictionaries Definition of fibrosis in the US English dictionary