For words that only have 3 letters, there is absolutely no 4th letter. Such as with the word “incorporate”, there are no much more letters Later on and so must be the word "include". The word “addict” is from the BIP39 wordlist however you might have utilised “addi” for “addict”. https://keybookmarks.com/story19641993/considerations-to-know-about-bip39-word-list-pdf