For words that only have 3 letters, there isn't a 4th letter. For example with the word “incorporate”, there won't be any additional letters Later on and thus should be the word "include". The word “addict” is inside the BIP39 wordlist however , you might have used “addi” for “addict”. https://icelisting.com/story19941684/the-fact-about-valid-bip39-seed-phrase-that-no-one-is-suggesting