late 14c., gelee, gelle, gelly, "semisolid substance from animal or vegetable material, spiced and used in cooking; chopped meat or fish served in such a jelly," from Old French gelee "a jelly," also "a frost," noun use of fem. past participle of geler "to congeal, to freeze," from Latin gelare "to freeze, congeal, stiffen," related to gelu "frost," from PIE *gela-, suffixed form of root *gel- "cold; to freeze."
By early 15c. it was used of any jellied or coagulated substance; from 16c. as "thickened juice of a fruit prepared as food."