For words that only have 3 letters, there isn't any 4th letter. By way of example with the word “include”, there are no a lot more letters afterwards and so needs to be the word "incorporate". The word “addict” is inside the BIP39 wordlist but you would've applied “addi” for https://bookmarkjourney.com/story19050175/an-unbiased-view-of-bip39-seed-phrase-github