For words that only have 3 letters, there is no 4th letter. By way of example with the word “add”, there won't be any a lot more letters afterwards and thus should be the word "incorporate". The word “addict” is in the BIP39 wordlist however , you might have utilized https://socialeweb.com/story4375794/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting