How do you define a muddy photo

A friend of mine recently took a series of portraits in natural light

in open shade. She said the photos turned out "muddy" and that the

lab told her it was because the pictures lacked contrast. She asked me

if it could be a lab processing error or her error (exposures, etc.).

My question is:

What exactly is the definition of muddy? Uncontrasty scene?

Underexposure?

I heard the term often but am not quite sure how one would define a

muddy photo.

Apologies in advance for a Photography 101 question.

As far as I know, there is no exact definition for "muddy." I tend to think of it as a

photograph without much contrast (either color, or luminance contrast).

A lack of contrast could be caused by any number of factors. Poor exposure, poor

processing or poor printing being chief among them.

It could have been the lab's screw up, but it could just as easily have been a mistake by the

photographer. And, of course, shooting in open shade will often reduce contrast, and

induce a blue cast in a scene as well.

I agree with Will's comments, but thought I'd also throw this in...

If the shots were taken digitally and she did some editing on her PC before uploading them to the lab, then it's quite possible she needs to calibrate her monitor. Before I calibrated my monitor, I took some shots, edited them to my liking on my PC and had them printed and the looked like complete crap. After I got my monitor calibrated I found out that the contrast on my monitor was waaaaay off and when I thought I was improving the shot I was actually making it very "muddy". After re-editing using my freshly calibrated monitor, the prints that came back from the lab looked exactly like what I saw on my monitor and were not muddy at all.