du·cal 
(dkəl, dy-)
(dkəl, dy-)adj.
Of or relating to a duke or duchy: a ducal estate.
[Middle English, from Old French, from Late Latin ducālis, from Latin dux, duc-, leader; see DUKE.]
ducal·ly adv.
- intermittent current
- intermittently
- intermitter
- intermix
- intermodal
- intermodulation
- intermontane
- intermountain
- in terms of
- intern
- internal
- internal-combustion engine
- internal ear
- internal energy
- internality
- internalization
- internalize
- internalizer
- internally
- internal medicine
- internal phase
- internal respiration
- internal rhyme
- internal secretion
- international