For words that only have three letters, there isn't any 4th letter. Such as with the word “incorporate”, there won't be any much more letters Later on and thus should be the word "increase". The word “addict” is during the BIP39 wordlist however, you would have employed “addi” for “addict”. https://eternalbookmarks.com/story18673837/top-guidelines-of-bip39-word-list-pdf