For words that have only three letters, there is not any 4th letter. By way of example with the word “increase”, there aren't any far more letters afterwards and so have to be the word "increase". The word “addict” is within the BIP39 wordlist however, you would have employed “addi” https://bookmark-dofollow.com/story21787127/the-greatest-guide-to-seed-phrase-bip39