Optical activity, also known as optical rotation, is a phenomenon in which a substance rotates the plane of polarized light. Some synonyms for optical activity include polarization rotation, optical polarization, polarimetry, and chiral activity. Polarimetry is a technique used to measure the degree of polarization rotation caused by a substance. Chiral activity specifically refers to optical activity caused by chiral molecules, which have non-superimposable mirror images. Optical polarization can also be used as a synonym for optical activity, as it refers to the way light waves align as they pass through a medium. Regardless of the synonym used, optical activity is an important property of many substances and plays a critical role in various scientific fields.