I have a txt file that lists about 170,000 words -- one word on each line. What's the easiest and fastest way for me to check if a work typed into a textbox exists in that word list file?

I was thinking of starting with the instr function. If it returns 0, then the word obviously doesn't exist in the file. But if instr returns something greater than 0, it doesn't mean the word does exist in the file. For example, "fr" is not in the word list but would return a positive result because "frown" is a word in the list.

Does that mean that after getting a positive result from instr, that I have to check every single word? I could load the words into an array with no problem but is there another way?