Old English pæll "rich cloth or cloak, purple robe, altar cloth," from Latin pallium "cloak, coverlet, covering," in Tertullian, the garment worn by Christians instead of the Roman toga; related to pallo "robe, cloak," palla "long upper garment of Roman women," perhaps from the root of pellis "skin." Notion of "cloth spread over a coffin" (mid-15c.) led to figurative sense of "dark, gloomy mood" (1742).
"become tiresome," 1700, from Middle English pallen "to become faint, fail in strength" (late 14c.), shortened form of appallen "to dismay, fill with horror or disgust" (see appall). Related: Palled; palling.