Posture: The carriage of the body as a whole, the attitude of the body, or the position of the limbs (the arms and legs).
"Postural" pertains to the posture or position. For example, postural hypotension is a drop in blood pressure (hypotension) due to a change in body position (a change in posture) when a person moves to a more vertical position: from sitting to standing or from lying down to sitting or standing.
The root of the word "posture" is the Latin verb "ponere" meaning "to put or place." The past participle "positus" gave the noun "positura" that travelled via France to England in the 16th century as "posture."