For words that have only 3 letters, there is not any 4th letter. By way of example with the word “incorporate”, there are no more letters Later on and thus need to be the word "include". The word “addict” is while in the BIP39 wordlist however you would've utilized “addi” https://easiestbookmarks.com/story18930938/a-review-of-bip39-phrase-list