For words that have only 3 letters, there is no 4th letter. One example is with the word “incorporate”, there are no a lot more letters Later on and thus have to be the word "incorporate". The word “addict” is while in the BIP39 wordlist however, you might have utilized https://bookmarkassist.com/story18767534/facts-about-bip39-seed-phrase-word-list-revealed