noun

1. 1. Archaic a mustache
   2. the hair growing on a man's face; esp., the beard on the cheeks
2. 1. a hair of a man's beard
   2. any of the long, bristly hairs growing on each side of the upper lip of a cat, rat, etc.; vibrissa
3. a very small, hairlike, single-crystal filament of high tensile strength, grown on certain metals, alloys, crystals, etc. and serving to reinforce the material
4. a very small amount or margin to lose an election by a whisker
5. Naut. either of two spars extending laterally one on each side of the bowsprit, for spreading the jib and flying jib guys
   also whisker boom

Etymology: ME wisker, something used for whisking: see whisk & -er