hickwall

hickwall local.
  (ˈhɪkwəl)
  Forms: α. 5 hyghwhele, 6 highwale, hucholl, hewhall, 6–7 hewel(l, 7– hew-hole. β. 7 highaw(e, heighaw, heyhoe, hiho, 7–8 high-hoe, 9 haihow; 9 heighhold. (Cf. high-hole, hecco.) γ. 6 hechewall, 6– hickwall; also 6 hicwaw, 7 hicway, 7–8 hickway. (Cf. witwall.) δ. 9 hickle, hickol, heckle, ickwell, ickle, eckle, eacle, eaqual, ecall, eikle, eekle. (Cf. yuckle.) ε. 8 hufil, 9 hefful. (Cf. yaffle.)
  [A word of comparatively late appearance in writing, of which the original form and derivation are difficult to determine amid the variety of spellings in which it is found from the 16th c. onwards. It is probable that all these go back to imitations of the ‘loud laughing note’ of the bird, of which the early form hygh-whele (? = hyxwɛl) may be an imitation (already perhaps modified so as to make it articulate). Closely allied to this are the series hueholl, hewhole, and heighaw, high-hoe, highhole, accommodated by popular etymology to the habits of the bird. The series hickwall, hicwaw, hickway may easily have arisen from an earlier (hyxwɛl), by the hardening of gh to k (as in heahfore, heyghfer, hekfer, heckfer (heifer), and the words hext, next), although the second element takes the appearance of being = OE. waᵹ, ME. wagh, and mod. wall, and the first has been explained as a derivative form of hack vb., quasi ‘that which hacks walls’. From hickwaw Drayton's hecco, and the modern hickle, ickle series, are obvious phonetic descendants. Finally, hefful, hufil, show f for earlier gh (x), and thus attach themselves likewise to (hyxwɛl). There is perh. some attraction between some of these forms and the names yuckle, yaffle, which appear to represent an earlier *youchel, *yawchel, parallel to (hyxwɛl); and there may have been similar mutual influence between hickwall and witwall, the latter prob. orig. = ME. wodewale, woodwall.]
  The Green Woodpecker.

Oxford English Dictionary