For words that only have 3 letters, there is not any 4th letter. For instance with the word “increase”, there won't be any a lot more letters afterwards and therefore must be the word "insert". The word “addict” is during the BIP39 wordlist however, you would have applied “addi” for https://myeasybookmarks.com/story4664163/top-guidelines-of-bip39-word-list-pdf