crest (n.)

early 14c., "highest part of a helmet," an extended sense, from Old French creste "tuft or tuft-like growth on the top of an animal's head, comb" (12c., Modern French crête), from Latin crista "tuft, plume," which is derived from the same source as words for "hair" (such as crinis, crispus), but it also was used for crest of a cock or the upright ornaments of a helmet. Said by Watkins to be from an extended form of PIE root *sker- (2) "to turn, bend." Replaced Old English hris.

The "tuft of an animal" sense is from late 14c. in English.Meaning "highest part of a hill or mountain range" is from late 14c.

late 14c., "provide with a crest," from Old French crester (12c.), from creste (see crest (n.)). Meaning "to come over the top ('crest') of" is from 1832; intransitive sense of "form or rise in a crest, reach the highest point" is from 1850. Related: Crested; cresting.