IMP (0. Eng. impa, a graft, shoot; the verb impian is cognate with Ger. impfen, to graft, inoculate, and the Fr. enter; the ultimate origin is probably the Gr. tfi<j>veiv, to implant, cf. efitpvros, engrafted), originally a slip or shoot of a plant or tree used for grafting. This use is seen in Chaucer (Prologue to the Monk's Tale, 68) " Of fieble trees ther comen wrecched ympes." The verb " to imp " in the sense of " to graft " was especially used of the grafting of feathers on to the wing of a falcon or hawk to replace broken or damaged plumage, and is frequently used metaphorically. 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." The New English Dictionary quotes an epitaph (1584) in the Beauchamp chapel at Warwick, " Heere resteth the body of the noble Impe Robert of Dudley . . . sonne of Robert Erie of Leycester." The current use of the word for a small devil or mischievous sprite is due to the expressions " imp of Satan, or of the devil or of hell," in the sense of " child of evil." It was thus particularly applied to the demons supposed to be the " familiar " spirits of witches.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)