For words that only have three letters, there isn't a 4th letter. Such as with the word “increase”, there aren't any a lot more letters afterwards and therefore have to be the word "add". The word “addict” is within the BIP39 wordlist however, you would've made use of “addi” for https://social-galaxy.com/story4285247/the-2-minute-rule-for-bip39-all-words