RUDACEOUS Meaning of RUDACEOUS in English [ rʊ'deɪʃəs ]■ adjective Geology (of rock) composed of fragments of relatively large size (larger than sand grains).Originearly 20th cent.: from L. rudus 'rubble' + -aceous . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004