glucose n.

before vowels, gluc-, word-forming element used since c. 1880s, a later form of glyco-, from Greek glykys "sweet," figuratively "delightful; dear; simple, silly," from *glku-, a dissimilation in Greek from PIE root *dlk-u- "sweet" (source also of Latin dulcis). De Vaan writes that "It is likely that we are dealing with a common borrowing from an unknown source." Now usually with reference to glucose.

1893, from Latinized form of Greek elements hypo- "under" (see hypo-) + glykys "sweet" (see glucose) + haima "blood" (see -emia).