For words that have only 3 letters, there's no 4th letter. One example is with the word “include”, there aren't any a lot more letters Later on and thus must be the word "increase". The word “addict” is while in the BIP39 wordlist however , you would have applied “addi” https://totalbookmarking.com/story19647173/invalid-bip39-phrase-things-to-know-before-you-buy