For words that only have three letters, there's no 4th letter. For example with the word “incorporate”, there aren't any much more letters Later on and thus have to be the word "include". The word “addict” is while in the BIP39 wordlist but you would've utilized “addi” for “addict”. A https://getsocialnetwork.com/story4437346/ledger-seed-phrase-bip39-no-further-a-mystery