For words that have only three letters, there is no 4th letter. Such as with the word “incorporate”, there are no additional letters afterwards and therefore has to be the word "increase". The word “addict” is during the BIP39 wordlist however , you would have used “addi” for “addict”. Numerous https://hindibookmark.com/story20471534/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-definition