| indispensable(adjective, characteristic, essential, basic, fundamental) |
| inmost(adjective, essential, basic, intimate, fundamental) |
| innermore(adjective, close, inside, central, interior) |
| innermost(adjective, intimate, secret, private, penetrating) |
| inseparable(adjective, intrinsic) |
| intestine(adjective, inside, interior, inner, internal) |
| intramural(adjective, inside, interior, inner, internal) |
| inwrought |
| municipal(adjective, inside, interior, inner, internal) |
| national(adjective, inside, interior, inner, internal) |
| original(adjective, characteristic, body, material, true) |
| peculiar(adjective, individual, essential, basic, fundamental) |
| penetrating(adjective, intimate, secret, private, personal) |
| perceptive(adjective, spontaneous, instinctive, intuitive) |
| privy(adjective, intimate, secret, private, penetrating) |
| repressed(adjective, individual, essential, private, mental) |
| resident(adjective, characteristic, natural, individual, essential) |
| special(adjective, individual, intimate, secret, private) |
| subconscious(adjective, individual, essential, private, mental) |
| thorough(adjective, complete, utter, intimate, secret) |