For words that have only three letters, there is no 4th letter. For instance with the word “insert”, there are no more letters Later on and thus should be the word "add". The word “addict” is within the BIP39 wordlist but you would've utilized “addi” for “addict”. Unlock your electronic https://johsocial.com/story9183180/bip39-seed-phrase-fundamentals-explained