For words that only have 3 letters, there isn't any 4th letter. Such as with the word “insert”, there won't be any much more letters Later on and therefore have to be the word "increase". The word “addict” is during the BIP39 wordlist however, you might have used “addi” for https://growthbookmarks.com/story18926535/the-greatest-guide-to-seed-phrase-bip39