early 15c., "a lobe of the liver or lungs," from Medieval Latin lobus "a lobe," from Late Latin lobus "hull, husk, pod," from Greek lobos "lobe, lap, slip; vegetable pod," used of lap- or slip-like parts of the body or plants, especially "earlobe," but also of lobes of the liver or lungs, a word of unknown origin. It is perhaps related to Greek leberis "husk of fruits," from PIE *logwos. Beekes writes that the proposed connection with the PIE source of English lap (n.1)) "is semantically attractive." Extended 1670s to divisions of the brain; 1889 to ice sheets. The common notion is "rounded protruding part."