IMP, originally a shoot of a plant or tree used for grafting (O.E. impa, a graft, shoot). The verb "to imp" was especially used of the grafting of feathers on to the wing of a falcon or hawk to replace broken plumage, and is frequently used meta phorically. Like "scion," "imp" was, till the 17th century, used of a member of a family, especially of high rank, hence often used as equivalent to "child."