Definitions of crest:

• noun:   a showy growth of e.g. feathers or skin on the head of a bird or other animal
• noun:   (heraldry) in medieval times, an emblem used to decorate a helmet
• noun:   the top line of a hill, mountain, or wave
• noun:   the center of a cambered road
• noun:   the top point of a mountain or hill
• verb:   reach a high point

  Example: "The river crested last night"

• verb:   lie at the top of
• name:  A surname (very rare: popularity rank in the U.S.: #47837)