What is the definition or description of: benzodiazepines level?

Blood level: Testing blood levels of benzodiazepines is not a routine or common clinical test. It is done by simply taking a blood sample and testing it in the lab. It is most commonly done in research studies. An example of clinical use would be when there is a discrepancy between the prescribed dosage and the effect suggesting overuse.

How much onboard: We measure how much of a medication is in your system, actually affecting you, by measuring how much is present in a standard amount of your blood ("blood level"). It's not the absolute dose you take, but the total dose present after a while of taking it distributed all over your body (so level = "concentration"). A small dose is a small person may be the same as a large dose in a large person.