tump vs whaleback

tump

noun
  • A tumpline. 

  • A mound or hillock. 

verb
  • To form a mass of earth or a hillock around. 

  • To fall over. 

  • To draw or drag, as a deer or other animal after it has been killed. 

  • to bump, knock (usually used with "over", possibly a combination of "tip" and "dump") 

whaleback

noun
  • A kind of cargo steamship with a hull that continuously curves above the waterline from vertical to horizontal. 

  • A landform (typically a sand dune) having the form of the back of a whale. 

How often have the words tump and whaleback occurred in a corpus of books? (source: Google Ngram Viewer )