For words that have only 3 letters, there is no 4th letter. For example with the word “increase”, there are no far more letters afterwards and therefore should be the word "include". The word “addict” is during the BIP39 wordlist however you would've made use of “addi” for “addict”. bip39-phrase.com https://bookmarkboom.com/story18823373/new-step-by-step-map-for-bip39-english-words