Webster's Revised Unabridged Dictionary · 1913

dilly

dilly (dil"ly) , noun

[Contr. from diligence.]

A kind of stagecoach.
The Derby dilly. — J. H. Frere

dilly (dil"ly) , noun

something remarkable, highly unusual, or exceptionally effective; as, a dilly of a movie; when I make a mistake, it's a dilly.