Upright position, standing
The upright, or erect, position of the human body.
The term "orthostatic" relates to the upright position of the body; the term is used when describing this position or a condition caused by it. Orthostatic hypotension, for example, is low blood pressure found in some people when they stand upright.
In medicine, orthostatic refers to the state of standing. It is most frequently used to describe the condition orthostatic hypotension (ICD-9 458.0), which means an unusually low blood pressure when the patient is standing up.