For words that have only 3 letters, there's no 4th letter. Such as with the word “increase”, there are no additional letters Later on and therefore has to be the word "incorporate". The word “addict” is in the BIP39 wordlist however, you might have used “addi” for “addict”. Artwork is https://socialdummies.com/story3741890/little-known-facts-about-bip39-seed-phrase-list