Sentence:  With a small <WSD>billhook</WSD> he carefully freed the collar of the tree from twigs and patches of moss which incrusted it to a height of a foot or two above the ground, an operation comparable to the "little toilet" of the executioner's victim. 
Meaning of the word marked with <WSD> tags:  An agricultural implement often with a curved or hooked end to the blade used for pruning or cutting thick, woody plants.