| A | B |
| immobility | the state of being without movement or motion |
| imperfect | flawed; defective; inferior |
| improbable | unlikely; doubtful |
| improper | not correct; unsuitable |
| inability | lack of aptitude, knowledge or skill |
| inadequate | not sufficient, unsatisfactory |
| inarticulate | having to do with unclear or mumbled speech |
| incapacitate | to take away strength or ability; to disable |
| incomprehensible | not able to be understood or believed |
| incongruity | a lack of correspondence; incompatibility |
| indefinite | not certain; not decided |
| indisputable | unquestionable; beyond doubt |
| inefficient | having to do with wasting time, space, or materials |
| inept | not qualified; unfit |
| informal | casual; lacking ceremony |
| inscrutable | mysterious; difficult to comprehend |
| invulnerable | not capable of being damaged, wounded or hurt |
| irreconcilable | not able to be resolved or restored to friendship or harmony |
| irreparable | unable to be corrected or fixed |
| irreversible | not able to be turned backward or changed to an opposite position or condition |