For words that have only 3 letters, there is not any 4th letter. One example is with the word “increase”, there won't be any additional letters afterwards and therefore should be the word "increase". The word “addict” is inside the BIP39 wordlist however , you would have used “addi” for https://freebookmarkpost.com/story18711651/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-definition