What does "lobe" mean?

Lobe: Any projection or division, especially one of a somewhat rounded form; as: (a) (Bot.) A rounded projection or division of a leaf. Gray. (b)(Zoöl.) A membranous flap on the sides of the toes of certain birds, as the coot. (c) (Anat.) A round projecting part of an organ, as of the liver, lungs, brain, etc. See Illust. of Brain. (b) (Mach.) The projecting part of a cam wheel or of a non-circular gear wheel. Lobe of the ear, the soft, fleshy prominence in which the human ear terminates below. See. Illust. of Ear.