For words that have only 3 letters, there isn't a 4th letter. Such as with the word “include”, there aren't any much more letters Later on and thus have to be the word "increase". The word “addict” is within the BIP39 wordlist but you would have used “addi” for “addict”. https://onlybookmarkings.com/story19072766/considerations-to-know-about-bip39-seed-phrase-generator