For words that only have three letters, there is absolutely no 4th letter. By way of example with the word “include”, there are no far more letters afterwards and therefore must be the word "increase". The word “addict” is while in the BIP39 wordlist however , you might have made https://socialistener.com/story4307033/how-much-you-need-to-expect-you-ll-pay-for-a-good-valid-bip39-seed-phrase