For words that only have 3 letters, there's no 4th letter. Such as with the word “insert”, there are no much more letters Later on and thus have to be the word "include". The word “addict” is during the BIP39 wordlist however , you might have utilized “addi” for “addict”. https://bouchesocial.com/story20768998/top-latest-five-bip39-words-urban-news