For words that only have 3 letters, there's no 4th letter. Such as with the word “include”, there aren't any far more letters afterwards and so need to be the word "insert". The word “addict” is while in the BIP39 wordlist however, you would have employed “addi” for “addict”. Standard https://bookmarkprobe.com/story19735851/considerations-to-know-about-bip39-word-list-pdf