inane
senseless, stupid, crazy
incredulous (incredulity)
skeptical, unbelieving
incriminate
accuse someone of a crime
incubate
develop, grow
indeterminate
left doubtful, inconclusive
indict(ment)
formally accuse of a crime
indigenous
native to a region
indignant
angered (by injustice)
indiscriminate
random
indolent
lazy
indomitable
too strong to be defeated
induce
cause
indulgent
lenient
ineffable
impossible to express in words
inepitable
incompetence
ingenuous
unsophisticated and trusting, naive
inherent
intrinsic, trusting
innocuous
harmless
innuendo
implicit suggestion
inscrutable
mysterious
insipid
dull, boring
insolence (insolent)
disrespectful
instigate
provoke, start
insular(ity)
related to an island
intrepid
courageous