1.NounAn obsolete unit of length defined as 6 inches, which equals 2 palms or ⁄3 span; today 6 inches equals exactly 15.24 cm. (Before the 12th century, a shaftment was defined as 6+⁄2 inches.)
2.NounTraditionally the width of the fist and outstretched thumb.
"A shaftment is the width of the palm and the outstretched thumb."