sloped vs tipping

sloped

adj
  • That has or have a slope. 

tipping

noun
  • A distinct articulation given in playing quick notes on the flute, by striking the tongue against the roof of the mouth; double-tonguing. 

  • The act by which something is tipped or inclined. 

  • The practice of leaving a tip (gratuity). 

  • A competition where entrants aim to tip (predict) the outcomes of sporting events. 

  • The dumping of rubbish. 

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