For words that only have 3 letters, there is no 4th letter. Such as with the word “incorporate”, there are no additional letters afterwards and thus needs to be the word "incorporate". The word “addict” is in the BIP39 wordlist however , you would have applied “addi” for “addict”. Meticulously https://lingeriebookmark.com/story8736210/the-5-second-trick-for-ledger-seed-phrase-bip39