For words that have only three letters, there isn't a 4th letter. As an example with the word “add”, there isn't any extra letters Later on and therefore must be the word "increase". The word “addict” is from the BIP39 wordlist however you might have used “addi” for “addict”. Mnemonic https://bookmark-media.com/story18941266/detailed-notes-on-copyright-wallet-seed-phrase-out-of-bip39