lanugo

noun

1. (countable, uncountable)Soft down or fine hair, specifically that covering the human foetus or a tumorous area.

   “From the presence of the woolly hair or lanugo on the human fœtus, and of rudimentary hairs scattered over the body during maturity, we may infer that man is descended from some animal which was born hairy and remained so during life.”

   “[…] early spring mountains with young-elephant lanugo along their spines […]”