crest vs decline

crest

noun
  • The top line of a slope or embankment. 

  • The plume of feathers, or other decoration, worn on or displayed on a helmet; the distinctive ornament of a helmet. 

  • The upper curve of a horse's neck. 

  • The ridge or top of a wave. 

  • A tuft, or other natural ornament, growing on an animal's head, for example the comb of a cockerel, the swelling on the head of a snake, the lengthened feathers of the crown or nape of bird, etc. 

  • The ornamental finishing which surmounts the ridge of a roof, canopy, etc. 

  • A ridge along the surface of a bone. 

  • A design or logo, especially one of an institution, sports club, association or high-class family. 

  • Any of several birds in the family Regulidae, including the goldcrests and firecrests. 

  • The summit of a hill or mountain ridge. 

  • The helm or head, as typical of a high spirit; pride; courage. 

  • A bearing worn, not upon the shield, but usually on a helmet above it, sometimes (as for clerics) separately above the shield or separately as a mark for plate, in letterheads, and the like. 

verb
  • Particularly with reference to waves, to reach a peak. 

  • To mark with lines or streaks like waving plumes. 

  • To reach the crest of (a hill or mountain) 

  • To furnish with, or surmount as, a crest; to serve as a crest for. 

decline

noun
  • A sloping downward, e.g. of a hill or road. 

  • A weakening. 

  • Downward movement, fall. 

  • A reduction or diminution of activity. 

  • The act of declining or refusing something. 

verb
  • To choose not to do something; refuse, forbear, refrain. 

  • To run through from first to last; to recite in order as though declining a noun. 

  • To cause to decrease or diminish. 

  • To bend downward; to bring down; to depress; to cause to bend, or fall. 

  • To turn or bend aside; to deviate; to stray; to withdraw. 

  • To move downwards, to fall, to drop. 

  • To inflect for case, number, gender, and the like. 

  • To reject a penalty against the opposing team, usually because the result of accepting it would benefit the non-penalized team less than the preceding play. 

  • To become weaker or worse. 

  • To recite all the different declined forms of (a word). 

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