Sentence:  But he did not notice , and was already backing the car down to the road , saying `` Toot-toot '' ! to the <WSD>stump</WSD> of a tree as he passed it , the same stump which had impaled the car of many a guest in the past thirty years and which he refused to have removed . 
Meaning of the word marked with <WSD> tags:  the base part of a tree that remains standing after the tree has been felled