For words that have only three letters, there isn't a 4th letter. Such as with the word “add”, there isn't any additional letters afterwards and thus must be the word "insert". The word “addict” is while in the BIP39 wordlist but you would've utilized “addi” for “addict”. Retailer your phrase https://thebookmarkid.com/story19036929/the-2-minute-rule-for-bip39-all-words