DITHYRAMBIC is a 11 letter word that starts with D.
Webster's 1913 Dictionary
Definition:
\Dith`y*ram"bic\, a. [L. dithyrambicus, Gr. ?: cf.
F. dithyrambique.]
Pertaining to, or resembling, a dithyramb; wild and
boisterous. ``Dithyrambic sallies.'' --Longfellow. -- n. A
dithyrambic poem; a dithyramb.
WordNet Dictionary