In anatomical terms, an afferent is a vessel or other conduit that brings substances towards a central area, which is often a major organ like the brain or the heart. It is the opposite of an efferent vessel, which carries substances away from these central locations.
The system of imperial units or the imperial system (also known as British Imperial) is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced.
British Imperial System. 1  traditional system of weights and measures used officially in Great Britain from 1824 until the adoption of the metric system beginning in 1965. The United States Customary System of weights and measures is derived from it.