For words that have only 3 letters, there is not any 4th letter. Such as with the word “add”, there isn't any much more letters Later on and therefore has to be the word "insert". The word “addict” is from the BIP39 wordlist however, you might have used “addi” for https://bookmarkdistrict.com/story18787254/bip39-seed-phrase-mnemonics-generator-an-overview