Definition of choil:
(n) :
An unsharpened portion of a knife blade at the base of the blade, near the handle of the knife.
(n) :
The region of a knife where such a portion is, or would be if it existed; the region may be arranged as a grip, guard, or combination thereof (a finger choil), or it may be a notch demarking the end of the sharpened edge (a sharpening choil).
(n) :
(on folding knives) The indentation of a pocket-knife blade where it joins the tang.
(n) :
(on fixed-blade knives) The portion where the heel meets the bolster.