Meaning of calvus

cal•vus

Pronunciation: (kal'vus), [key]
— adj. Meteorol.
  1. (of a cumulonimbus cloud) having its upper portion changing from a rounded, cumuliform shape to a diffuse, whitish, cirriform mass with vertical striations.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.