For words that only have 3 letters, there is absolutely no 4th letter. For example with the word “incorporate”, there aren't any much more letters afterwards and so have to be the word "add". The word “addict” is inside the BIP39 wordlist however , you would have used “addi” for https://fellowfavorite.com/story20031568/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news