musculous UK /ˈmʌ.skjʊl.əs/US /ˈmʌ.skjəl.əs/ adjective3 •(no longer used) Made up of muscle or muscle tissue; muscular. •(no longer used) Pertaining to muscle; involving the use of muscles; muscular. •(no longer used) Characterised by well-developed muscles; muscular, muscly. formsmore musculous · most musculous