Dextro-

Dextrorotation is the property of rotating plane polarized light clockwise. Laevorotation is the opposite of dextrorotation.Compounds with these properties are said to have optical activity and consist of chiral molecules. Chiral centers that have opposite configurations rotate polarized light the same number of degrees, but in opposite directions. If one molecule that has a chiral center with an "R" configuration rotates plane polarized light 25 degrees clockwise, its enantiomer with the corresponding chiral center having the "S" configuration will rotate plane polarized light 25 degrees counter-clockwise. However it is not possible to determine whether any chiral center will be laevorotatory or dextrorotatory directly from its configuration. Enantiomers have equal and opposite optical rotation, but both "R" and "S" stereocenters have the ability to be dextrorotatory or laevorotatory.
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having the property of turning the plane of polarized light to the right; as, dextrotartaric acid.
  

A prefix, from L. dexter, meaning, pertaining to, or toward, the right
  

From the Latin dexter meaning on the right side. For example, a molecule that shows dextrorotation is turning or twisting to the right. The opposition of dextro- is levo- (from the Latin laevus meaning on the left side) so the opposite of dextrorotation is levorotation.

prf. ขวามือ, ด้านขวามือ (syn. dextral, dexter)