thun·der·head 
(thŭndər-hĕd′)
(thŭndər-hĕd′)n.
The swollen upper portion of a thundercloud, usually associated with the development of a thunderstorm.
- irrelevantly
- irreligion
- irreligious
- irreligiously
- irreligiousness
- irremeable
- irremediable
- irremediably
- irremissibility
- irremissible
- irremissibly
- irremovability
- irremovable
- irremovably
- irreparability
- irreparable
- irreparableness
- irreparably
- irrepealable
- irreplaceability
- irreplaceable
- irreplaceableness
- irreplaceably
- irrepressibility
- irrepressible