For words that only have 3 letters, there is no 4th letter. As an example with the word “include”, there isn't any far more letters afterwards and so have to be the word "insert". The word “addict” is within the BIP39 wordlist however , you would have used “addi” for https://opensocialfactory.com/story19327395/ledger-seed-phrase-bip39-no-further-a-mystery