For words that have only three letters, there is not any 4th letter. Such as with the word “insert”, there are no more letters afterwards and thus must be the word "include". The word “addict” is during the BIP39 wordlist but you might have made use of “addi” for “addict”. https://bookmarkfly.com/story19045589/examine-this-report-on-bip39-passphrase