For words that have only 3 letters, there isn't any 4th letter. For instance with the word “add”, there isn't any a lot more letters Later on and therefore needs to be the word "add". The word “addict” is within the BIP39 wordlist however, you would've made use of “addi” https://digibookmarks.com/story18870473/bip39-seed-phrase-fundamentals-explained