For words that only have three letters, there is no 4th letter. For example with the word “insert”, there aren't any extra letters afterwards and so has to be the word "increase". The word “addict” is while in the BIP39 wordlist but you would have utilized “addi” for “addict”. gravity https://bookmarkrange.com/story20216907/considerations-to-know-about-bip39-word-list-pdf