For words that only have three letters, there isn't any 4th letter. Such as with the word “incorporate”, there are no additional letters Later on and thus has to be the word "add". The word “addict” is while in the BIP39 wordlist however you would've used “addi” for “addict”. Mnemonic https://socialfactories.com/story4267928/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news