For words that have only 3 letters, there isn't any 4th letter. For example with the word “add”, there won't be any a lot more letters Later on and thus must be the word "incorporate". The word “addict” is within the BIP39 wordlist however, you would've employed “addi” for “addict”. https://alphabookmarking.com/story18843454/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news