Are the words ציפור (bird) and ציפורן (finger nail OR a spice [found in k'tores]) etymologically related? I heard that both were connected to the root צ.פ.ר (arise) or to anatomical protuberance but I don't understand either of these suggestions.
The derivation of צפור is obscure. It is to be found in צפורן, nail, and in צפיר, synonymous with שעיר the hairy one, the goat. So that צפור could be the bird called after its covering with feathers, the feathered one. The root צפר would then be common for nails, hair and feathers which are all three really derivatives fundamentally from the same tissue, (the epidermis I.L.).