For words that only have three letters, there isn't a 4th letter. Such as with the word “increase”, there aren't any far more letters Later on and so should be the word "add". The word “addict” is within the BIP39 wordlist however , you would have utilized “addi” for “addict”. https://prbookmarkingwebsites.com/story22158079/how-much-you-need-to-expect-you-ll-pay-for-a-good-valid-bip39-seed-phrase