For words that only have three letters, there isn't a 4th letter. One example is with the word “insert”, there aren't any much more letters Later on and so has to be the word "incorporate". The word “addict” is in the BIP39 wordlist but you might have utilized “addi” for https://greatbookmarking.com/story18864585/the-definitive-guide-to-bip39-seed-phrase