For words that only have 3 letters, there isn't any 4th letter. Such as with the word “incorporate”, there won't be any far more letters Later on and so must be the word "incorporate". The word “addict” is within the BIP39 wordlist but you would've utilised “addi” for “addict”. This https://myfirstbookmark.com/story18884878/bip39-seed-phrase-mnemonics-generator-an-overview