For words that only have 3 letters, there isn't a 4th letter. As an example with the word “increase”, there isn't any more letters Later on and so must be the word "increase". The word “addict” is while in the BIP39 wordlist however you would've made use of “addi” for https://open.substack.com/pub/jaidenqrel955/p/unlocking-the-power-of-bip39-how?r=54uq0h&utm_campaign=post&utm_medium=web&showWelcomeOnShare=true