For words that only have three letters, there is no 4th letter. As an example with the word “increase”, there isn't any extra letters Later on and so needs to be the word "include". The word “addict” is within the BIP39 wordlist but you might have utilised “addi” for “addict”. https://bookmark-vip.com/story19015746/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news