For words that only have three letters, there isn't a 4th letter. As an example with the word “add”, there won't be any a lot more letters Later on and therefore must be the word "include". The word “addict” is within the BIP39 wordlist but you would've applied “addi” for https://techonpage.com/story4238721/bip39-seed-phrase-mnemonics-generator-an-overview