Meaning of thunderhead

thun•der•head

Pronunciation: (thun'dur-hed"), [key]
— n. Meteorol.
  1. incus (def. 2).
  2. cumulonimbus.
  3. the upper portion of a cumulus cloud characterized by dense, sharply defined, cauliflowerlike upper parts and sometimes by great verticality.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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