For words that only have three letters, there isn't any 4th letter. For example with the word “add”, there isn't any a lot more letters afterwards and thus should be the word "insert". The word “addict” is inside the BIP39 wordlist however you might have applied “addi” for “addict”. An https://livebackpage.com/story4401854/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator