For words that have only 3 letters, there is absolutely no 4th letter. For instance with the word “include”, there are no a lot more letters afterwards and therefore has to be the word "add". The word “addict” is during the BIP39 wordlist however, you would have utilised “addi” for https://wavesocialmedia.com/story4545085/ledger-seed-phrase-bip39-no-further-a-mystery