For words that only have 3 letters, there is absolutely no 4th letter. By way of example with the word “incorporate”, there aren't any a lot more letters afterwards and so must be the word "incorporate". The word “addict” is inside the BIP39 wordlist but you would've applied “addi” for https://top100bookmark.com/story19153345/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator