eave (n.)

"lower part of a roof," especially that which projects beyond the wall, 1570s, alteration of southwest Midlands dialectal eovese (singular), from Old English efes "edge of a roof," also "edge of a forest," from Proto-Germanic *ubaswo-/*ubiswo "vestibule, porch, eaves" (source also of Old Frisian ose "eaves," Old High German obasa "porch, hall, roof," German Obsen, Old Norse ups, Gothic ubizwa "porch;" German oben "above"), from extended form of PIE root *upo "under," also "up from under," hence also "over." Regarded as plural and a new singular form eave emerged 16c.