For words that have only three letters, there's no 4th letter. Such as with the word “add”, there won't be any much more letters Later on and so need to be the word "incorporate". The word “addict” is within the BIP39 wordlist however , you would have employed “addi” for https://bookmarkize.com/story18854570/the-definitive-guide-to-bip39-seed-phrase