implacable
not to be appeased or pacified
impugn
to challenge as false
indispensable
absolutely necessary
indignant
expressing strong displeasure at something offensive
inclined
having a tendency
indulgent
to give in to a desire in an excess manner
incorruptible
incapable of being morally corrupted
implicate
to show to also be involved, generally in crime
improvise
to compose, recite, or play on the spur of the moment
impetuous
having sudden or rash action
impudent
having or showing offensive boldness
inconsequential
of little or no importance
indisputable
not subject to argument or dispute
incongruous
out of place, unbecoming, or inappropriate
indifference
having no interest or concern
incorporate
to put into or introduce as an integral part
impose
to establish as a requirement
impulsive
done without thinking, swayed by emotional reasoning
ineffable
incapable of being expressed in words
incisive
remarkably clear and direct