1810-20; < Medieval Latingrīseus, based on Germanic*grīs or *grīsi gray, perhaps with suffix of Latinrūbeus; compare Old Saxongrîs gray Old French,Frenchgris gray; see -eous
British Dictionary definitions for griseous
griseous
/ˈɡrɪsɪəs; ˈɡrɪz-/
adjective
1.
streaked or mixed with grey; somewhat grey
Word Origin
C19: from Medieval Latin griseus, of Germanic origin