When written in upper case, some words have "vertical line symmetry," meaning that they appear the same when seen in the reflection of an upright mirror. MOM is one of these words. Other upper-case words have what's known as "horizontal line symmetry," meaning that they look identical when reflected in a still pool of water. COOK is such a word. MOM is not horizontally symmetrical, although it does form a different word (WOW) when viewed that way.

MOM SAYS: Please read ALL of the remainder of this post to ensure contest eligibility!

 

If you'll comment to this post with ONE symmetrical English word (horizontal or vertical) of your choice, I'll enter your email address in our "Mom is Wow" contest. Your comment must be dated May 7, 2009 to be eligible. IMPORTANT: Comments are moderated, so they don't show up right away, but all entries sent before midnight will be eligible.

Friday morning, I'll have the computer choose one entry at random, and if you're lucky, you'll win matching mental_floss T-shirts for you AND your mom! Don't worry if you offer a word that someone else has already given, but do try to come up with something original; we don't call this the Brain Game for nothing!

ONE ENTRY PER PERSON, AND NORTH AMERICAN ENTRIES ONLY, PLEASE. I'll announce the winner on the blog and notify him/her via email on Friday, and (given the necessary info and your permission) will drop your mom a personal email as well, explaining what a clever and caring person you are, that her Mother's Day gift is in the mail, and how you always wash behind your ears. Good luck!