07/09/2009 09:54 pm ET | Updated Nov 17, 2011

Caution: Frenemies Can Be Bad for Your Health

In my experience, whatever the problem, giving it a name is a first step in solving it. That's why I was pleased that Merriam-Webster included the word "fren-e-my" (plural: fren-e-mies) in the list of 100 new words it announced today that were added to the Collegiate Dictionary, Eleventh Edition.

The term frenemy, seamlessly blending the words fri(end) and enemy, refers to someone who pretends to be a friend but actually is an enemy -- a proverbial wolf in sheep's clothing in the world of friendships. If you think about it, most of us have had a frenemy at one time of another, either at school, at work, or lurking in our neighborhood.

She (or he) is likely to be a friend who is filled with ambivalence and jealousy. She admires you and wants to be close but feels like she can't hold a candle to you because (she thinks) you're smarter, thinner, richer, or more successful. Ostensibly, she is a friend -- but her covert hostility is an attempt to kick you down a notch and put you in your place. For example, she might be the master of the backhanded compliment who says something like, "You have such a pretty face. If you lost twenty pounds, you would really be attractive."

"You know a friend is really a frenemy if she brings out the worst in you and leaves you feeling drained," say Andrea Lavinthal and Jessica Rozler, co-authors of Friend or Frenemy?. "A sure sign you have a frenemy is when that person cancels plans with you, you're relieved instead of disappointed."

While most research on friendship and health has focused on the positive relationship between the two, a frenemy is a potential source of irritation and stress. One study by psychologist Dr. Julianne Holt-Lunstad found that unpredictable love-hate relationships characterized by ambivalence can lead to elevations in blood pressure. In a previous study, the same researcher found that blood pressure is higher around friends for whom we have mixed feelings than it is when we're around people whom we clearly dislike.

The term frenemy has been around for a while, reportedly coined by a sister of author and journalist Jessica Mitford in 1977, and popularized more than twenty years later on the third season of Sex and the City. But like "staycation, "earmark" and "physiatry" it was never legitimized by an entry in the dictionary. Now that it has been, assess that friendship that has always made you feel queasy and uncomfortable and give it a name. Then you'll realize it's time to let go or to find a way to fix it.

Have a question about female friendships? Send it to The Friendship Doctor.

Irene S. Levine, PhD is a freelance journalist and author. She holds an appointment as a professor of psychiatry at the New York University School of Medicine and her book about female friendships, Best Friends Forever: Surviving A Breakup With Your Best Friend, will be published by Overlook Press in September, 2009. She recently co-authored Schizophrenia for Dummies (Wiley, 2008). She also blogs about female friendships at The Friendship Blog.