Late 17th century; earliest use found in Randle Holme (1627–1700), herald painter. From classical Latin roseus made of roses, rose-coloured (from rosa + -eus: see -eous) + -ous.
Definition of roseous in US English:
roseous
adjectiveˈrəʊzɪəs
Rose-like, especially in colour.
Origin
Late 17th century; earliest use found in Randle Holme (1627–1700), herald painter. From classical Latin roseus made of roses, rose-coloured (from rosa + -eus: see -eous) + -ous.