Unlawful Versus Illegal

Today's topic is illegal versus unlawful.

Mignon Fogarty
3-minute read
Episode #68

A Note About Prefixes

Grammar Girl:

Interesting! So Jed had better not eat and rock out on the bus.

I found a couple of interesting things while I was reading about prefixes. First, un- (as in unlawful) is an English prefix, and in- (as in injustice) is the corresponding Latin prefix.

And then second, il- (as in illegal, illicit, and illegitimate) is considered to be a form of the prefix in- (as in injustice and indivisible).

It works a little bit like how you choose to use the words a or an depending on whether the next word starts with a consonant or vowel sound. In this case, the prefix in- gets changed to il- when the word starts with the letter l, and it also gets changed to im- when the word starts with a p or b, as in impossible and imbalance.

Web Bonus

The prefix in- has two meanings.

First, it can roughly mean the equivalent of the English word in, as in inclusive and inland. This version comes from Old English and Latin.

Second, it can roughly mean not, as in injustice and indivisible. This version comes from Latin.

That's all.

Thursday, July 26, was Grammar Girl's one year anniversary, and it's mind-boggling to think of all the things that have happened in the last year. It has all been because of you—the listeners—and your enthusiasm for the show, so thanks for everything. I'll do my best to make the second year as fun and interesting as the first.

While you're here on the Quick and Dirty Tips website, be sure to check out the other great podcasts such as Modern Manners. He answers tough questions like how to deal with uninvited guests.   

Thanks for listening.


  1. “In- as a Prefix,” The Maven's Word of the Day, New York: Random House, June 4, 1997 www.randomhouse.com/wotd/index.pperl?date=19970604 (accessed July 25, 2007).
  2. Wilson, K.G. “il-,”  The Columbia Guide to Standard American English. New York: Columbia University Press, 1993, www.bartleby.com/68/6/3106.html (accessed July 25, 2007).
  3. in-. Dictionary.com. Dictionary.com Unabridged (v 1.1). New York: Random House, Inc. dictionary.reference.com/browse/in- (accessed: July 26, 2007).
  4. in-. The American Heritage® Book of English Usage. Boston: Houghton Mifflin Company, 1996
    http://www.bartleby.com/64/pages/page247.html (accessed July 25, 2007).
  5. Xavier, J. “How Negative Prefixed Are Determined in English,” The Linguistic Zone, June 19, 2007, http://urltea.com/1ee9 (accessed July 26, 2007).


3D Judges Gavel image, Chris Potter at Flickr. CC BY 2.0.


About the Author

Mignon Fogarty

Mignon Fogarty is the founder of Quick and Dirty Tips and the author of seven books on language, including the New York Times bestseller "Grammar Girl's Quick and Dirty Tips for Better Writing." She is an inductee in the Podcasting Hall of Fame, and the show is a five-time winner of Best Education Podcast in the Podcast Awards. She has appeared as a guest expert on the Oprah Winfrey Show and the Today Show. Her popular LinkedIn Learning courses help people write better to communicate better.