For words that have only 3 letters, there isn't any 4th letter. For example with the word “include”, there isn't any far more letters Later on and thus needs to be the word "insert". The word “addict” is during the BIP39 wordlist however you would've utilized “addi” for “addict”. This https://ragingbookmarks.com/story18817779/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator