For words that only have three letters, there's no 4th letter. For example with the word “add”, there won't be any a lot more letters Later on and therefore needs to be the word "increase". The word “addict” is inside the BIP39 wordlist however , you might have utilized “addi” https://wearethelist.com/story21048275/the-definitive-guide-to-bip39-seed-phrase