For words that only have 3 letters, there isn't any 4th letter. For instance with the word “add”, there are no a lot more letters Later on and so have to be the word "incorporate". The word “addict” is within the BIP39 wordlist but you would have used “addi” for https://bookmarkinglog.com/story19029463/an-unbiased-view-of-bip39-seed-phrase-github