For words that only have 3 letters, there is no 4th letter. Such as with the word “incorporate”, there are no additional letters Later on and so need to be the word "include". The word “addict” is during the BIP39 wordlist however you would have used “addi” for “addict”. BIP39 https://sb-bookmarking.com/story18887271/facts-about-bip39-seed-phrase-word-list-revealed