For words that only have three letters, there isn't a 4th letter. One example is with the word “include”, there isn't any additional letters afterwards and therefore should be the word "add". The word “addict” is from the BIP39 wordlist but you might have made use of “addi” for “addict”. https://bookmarkmiracle.com/story20317491/the-fact-about-valid-bip39-seed-phrase-that-no-one-is-suggesting