For words that have only three letters, there isn't any 4th letter. Such as with the word “incorporate”, there are no extra letters Later on and thus needs to be the word "incorporate". The word “addict” is while in the BIP39 wordlist however you would've utilised “addi” for “addict”. A https://bookmarkuse.com/story18675601/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool