1510s, "of the color of blood, of a deep red color;" 1640s, "of or pertaining to blood," from Latin sanguineus "of blood, bloody," from sanguin-, stem of sanguis (see sanguinary).
Entries linking to sanguineous
sanguinary adj.
1620s, "characterized by slaughter, attended by much bloodshed;" also bloodthirsty, eager to shed blood, delighting in carnage," from French sanguinaire or directly from Latin sanguinarius "of or pertaining to blood," also, rarely, "blood-thirsty," from sanguis (genitive sanguinis) "blood," a word of unknown origin. Latin distinguished sanguis, the generic word, from cruor "blood from a wound" (related to English raw, from PIE root *kreue-). The classical sense of "pertaining to blood" is rare in English.