impermeable,that cannot be permeated
imperturbable,calm/not capable of being excited
impervious,not allowing to pass through (of materials)
imperviousness,arrogance/commanding presence/overbearingness 
impetuous,having sudden energy/impulsive/thrusting ahead
impiety,lack of reverence or dutifulness
implacable,incapable of being placated/unpleasable 
implausibility,incredibility
implicate,show that smb has a share
implication,that which is hinted at or suggested
implicit,implied though not plainly expressed
implosion,collapse/bursting inward
imply,make a suggestion
importune,beg urgently/solicit (of a prostitute)
impostor,someone who assumes a false identity
imprecation,an invocation of evil/a curse 
impromptu,without preparation
impudence,being rash/indisreet
impudent,rash/indiscreet
impugned,challenged/to be doubted
impute,to attribute to a cause or source/ascribe 
inadvertent,not paying proper attention
inane,silly/senseless
inasmuch,since/because
inaugurate,to start
incence,make angry
incessant,often repeated/continual
inchoate,not yet fully formed/rudimentary/elementary 
incise,engrave/make a cut in
incite,stir up/rouse
inclined,directing the mind in a certain direction
incoherently,not consistently/unclearly
incongruous,out of place/not in harmony or agreement
incorrigibility,cannot be cured or corrected
incredulous,skeptical/unwilling to believe
inculcate,fix firmly by repetition
incumbents,official duties
incursion,a raid/a sudden attack 
indefatigability,not easily exhaustible/tirelessness 
indelible,that cannot be rubbed out
indelicate,immodest/lacking in refinement
indigence,poverty
indigenous,native
indistinct,not easily heard/seen/clearly marked
indolence,laziness 
indomitable,not easily discouraged or subdued 
indulge,gratify/give way to/satisfy/allow oneself
indulgent,inclined to indulge
indulgent,humoring/yielding/lenient
ineffable,to great to be described in words