For words that have only three letters, there isn't a 4th letter. By way of example with the word “increase”, there aren't any extra letters Later on and therefore have to be the word "include". The word “addict” is within the BIP39 wordlist but you would've utilised “addi” for “addict”. https://bookmarkusers.com/story19427256/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news