For words that have only 3 letters, there isn't a 4th letter. One example is with the word “include”, there are no much more letters afterwards and therefore should be the word "insert". The word “addict” is inside the BIP39 wordlist however , you would have applied “addi” for “addict”. https://sites2000.com/story8440096/facts-about-bip39-seed-phrase-github-revealed