impeccable  | a. having no flaws; perfect; incapable of sin or wrongdoing  |  
 impecunious  | a. without money; poor; penniless  |  
 impede  | v. hinder; charge with improper conduct; challenge validity of; try to discredit  |  
 impel  | v. drive or force onward; drive forward; urge to action through moral pressure  |  
 impenitent  | a. impervious to moral persuasion; of hard heart  |  
 imperceptible  | a. impossible or difficult to perceive by the mind or senses  |  
 impermeable  | a. not allowing passage, especially of liquids; waterproof  |  
 imperturbable  | a. unshakably calm; placid; incapable of being disturbed or disconcerted  |  
 impervious  | a. cannot be penetrated or affected, immune  |  
 impetus  | n. incentive; stimulus; force or energy associated with a moving body  |  
 impinge  |  v. to encroach, transpass  |  
 implacable  | a. incapable of being pacified; not to be relieved;  |  
 importunate  | a. urging; demanding; expressing earnest entreaty  |  
 importune  | v. beg persistently; ask for urgently or repeatedly; annoy  |  
 impound  | v. to seize and retain in legal custody  |  
 impoverish  | v. make poor; reduce to poverty or indigence; exhaust the strength, richness, or fertility of  |  
 imprecation  | n. curse; act of calling down a curse that invokes evil  |  
 improvident  | a. thriftless; not providing for future; incautious  |  
 impugn  | v. dispute or contradict, often in insulting way; challenge  |  
 impute  | v. lay responsibility or blame for, often unjustly  |  
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