For words that only have 3 letters, there is not any 4th letter. As an example with the word “increase”, there are no a lot more letters afterwards and thus has to be the word "include". The word “addict” is from the BIP39 wordlist but you would've utilised “addi” for https://privatebin.net/?57c491b9cad17a10#2jP1wyi3VUgs8q9BTwvowdFnmCxc6BsRV7dxomBiXrt6