1. Turning or movement of a body around its axis. 2. A recurrence in regular order of certain events, such as the symptoms of a periodic disease. 3. In medical education, a period of time on a particular service or specialty. [L. rotatio, fr. roto, pp. rotatus, to revolve, rotate]
- intestinal r. r. of the primitive intestinal loop around an axis formed by the superior mesenteric artery. See malrotation.
- molecular r. one-hundredth of the product of the specific r. of an optically active compound and its molecular weight.
- optic r. the change in the plane of polarization of polarized light of a given wavelength upon passing through optically active substances; measured in terms of specific r. by polarimetry, an important tool in chemical structural work, especially on carbohydrates.
- specific optic r. ([α]) the arc through which the plane of polarized light is rotated by 1 g of a substance per milliliter of water when the length of the light path through the solution is 1 decimeter, typically using light corresponding to the D line of sodium.
* * *
ro·ta·tion rō-'tā-shən n the action or process of rotating on or as if on an axis or center specif the turning of a body part about its long axis as if on a pivot <\rotation of the head to look over the shoulder>
ro·ta·tion·al -shnəl, -shən-əl adj
* * *
ro·ta·tion (ro-taґshən) [L. rotare to turn] 1. the process of turning around an axis; movement of a body about its axis, called the axis of rotation. 2. the turning of the fetal head through 90 degrees during labor so that the long diameter of the head corresponds with the long diameter of the pelvic outlet. It should occur naturally, but if it does not the rotation may be accomplished manually or instrumentally by the obstetrician. See also maneuver. 3. a turning around a central axis without undergoing any displacement from the axis. See also hinge movement, under movement. 4. a procedure whereby a malturned tooth is turned into its normal position. 5. malposition due to an abnormal turning of a tooth around its longitudinal axis.Medical dictionary. 2011.