For words that only have 3 letters, there is no 4th letter. Such as with the word “include”, there isn't any much more letters Later on and so needs to be the word "insert". The word “addict” is from the BIP39 wordlist but you would have made use of “addi” https://bookmark-dofollow.com/story21733564/the-greatest-guide-to-seed-phrase-bip39