Complex sentence: Fibrosis is the formation or development of excess fibrous connective tissue in an organ or tissue as a reparative or reactive process, as opposed to a formation of fibrous tissue as a normal constituent of an organ or tissue.
Split into simpler sentences: Fibrosis is the formation or development of excess fibrous connective tissue in an organ or tissue as a reparative or reactive process. This is as opposed to formation of fibrous tissue as a normal constituent of an organ or tissue.