For words that have only three letters, there isn't any 4th letter. One example is with the word “incorporate”, there isn't any far more letters Later on and thus should be the word "increase". The word “addict” is during the BIP39 wordlist however, you would have applied “addi” for “addict”. https://fellowfavorite.com/story20339872/the-invalid-bip39-phrase-diaries