For words that only have 3 letters, there is not any 4th letter. As an example with the word “increase”, there isn't any far more letters Later on and therefore needs to be the word "include". The word “addict” is from the BIP39 wordlist but you might have utilised “addi” https://1001bookmarks.com/story18702529/a-review-of-bip39-passphrase