There are a wealth of diseases and disorders out there, but you might be throwing around a few terms that don't mean anything at all. That condition you just talked about with your best friend? You don't really have it. At least, not exactly. (The Power Nutrient Solution is the first-ever plan that tackles the root cause of virtually every major ailment today; get your copy today!) Here are a few commonly used—but medically inaccurate—"diagnoses."

Stomach flu
The flu, by definition, refers to a specific virus (influenza) that primarily wreaks havoc on the respiratory system.

"Influenza causes fever greater than 101°F with congestion or sore throat," said Dr. Jill Swartz, a physician with GoHealth Urgent Care in Westchester, NY. "It rarely causes stomach vomiting and diarrhea."

What you likely have is gastroenteritis, which is caused by a different virus (such as the norovirus), bacteria (such as E. coli), or parasites. Calling it a "stomach bug" or "stomach virus" is closer.

Walking pneumonia 
A medical professional might actually tell you that you have this, but it's something of a catch-all rather than an exact diagnosis. It could mean that you have a very mild case of pneumonia and don't require hospitalization, or it might just mean that you have a chronic cough and have been feeling cruddy for over a month but your doctor can't pinpoint why, Swartz said. When there's nothing conclusive going on, doctors will sometimes label patients with "walking pneumonia" and medicate them to see if it helps, she explains. "If you take a Z-Pak and it works, great. If not, then let's see if we can find another reason."

Gluten allergy

If gluten—proteins found in wheat, rye, and barley—makes you feel lousy, one of three things is likely going on, but none of them is a gluten allergy.

"Celiac disease, which is a serious condition, is an immune response to gluten, not an allergy like we think about a peanut allergy," said Dr. Janna Tuck, an allergist and spokesperson for the American College of Allergy, Asthma, and Immunology.

Some people have a wheat allergy, which means they can have a severe (even life-threatening) reaction to eating wheat, but they would be fine chowing down on barley. Not in either camp? You probably have gluten sensitivity, which simply means you get bloating, pain, or stomach cramps when you eat something with gluten in it.

Nervous breakdown 
"It's one of my least favorite terms," said Dr. Tamar Gur, PhD, a psychiatrist with Ohio State University's Wexner Medical Center. "When we get overwhelmed, we can feel like we are going to lose our minds, but we do not. People do not have mental breakdowns, which is how that term is usually used," she said.

If you ever hear that someone has been hospitalized for a "nervous breakdown," it likely means that he or she is suffering from a severe mental health episode, which could be related to any number of conditions (anxiety, depression, bipolar disorder, schizophrenia, etc.). Treatment should help.

MORE: 16 Signs Your Thyroid Is Out Of Whack

Head cold
While a cold may feel like it's centralized in your head or chest, a "head cold" is no different from a regular cold, which is caused by a virus. (The same goes for a "chest cold.") Your stuffiness or malaise may be concentrated in one area of your body, or the sensations may be a sign of sinusitis, inflammation of the sinus tissue.

"Does your head feel stuffed, or filled with fluid?" Swartz said. "It's more of a symptom than a diagnosis. You would never write, 'Diagnosis: head cold.' "

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