For words that have only 3 letters, there isn't a 4th letter. By way of example with the word “include”, there isn't any extra letters Later on and thus need to be the word "insert". The word “addict” is during the BIP39 wordlist but you would've made use of “addi” https://mediajx.com/story21479999/the-5-second-trick-for-ledger-seed-phrase-bip39