For words that only have 3 letters, there isn't any 4th letter. For instance with the word “add”, there are no a lot more letters afterwards and thus must be the word "incorporate". The word “addict” is from the BIP39 wordlist however , you would've utilized “addi” for “addict”. On https://thesocialintro.com/story5045517/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator