hollowing

noun2

1. •
   The process by which something becomes hollowed, or the result of that process.

   • Such hollowing is not seen in the smaller otoliths figured by Campana (herein reproduced on Pl. 5, Fig. 1) and by Ohe, and it may be a feature that […] — 2007
2. •
   The act of one who hollows (hollos); a cry or shouting.

   • At length, about three o'clock in the morning, we heard the distant hollowings of our watermen, and soon after refreshed ourselves with copious draughts of the delicious water of the Nile. — 1819