When a doctor orders laboratory tests, like blood tests for disease or for nutritional status, the doctor is the referring doctor: he refers the patient to the lab. In medicine, it approximately means sends, because the doctor is sending the patient to the lab, or other doctor, or . . .
Definitions for still waters run deep. Here are all the possible meanings and translations of the word still waters run deep. Wiktionary(0.00 / 0 votes)Rate this definition: still waters run deep(Proverb) A person with a calm appearance has, or may have, considerable inner emotion, character, or intellect.
That is what it *means* when we say it. But it comes from exactly what it sounds like. In nature, the more still the top of the water in a river, the deeper that part of the river is likely to be. Thus, still waters are deep waters while fast waters are shallow. All you can see is the surface, but you can tell a lot by that surface. Someone just applied that natural observation to a human personality trait - just like saying the 'early bird gets the worm' to indicate a hard worker that gets rewarded for their efforts.