What is a single oar that is moved from side to side over the stern of a boat to propel it?

The single oar moved from side to side over the stern of a boat to propel it is known as a "sculling oar." This technique is often used in small boats, where the rower uses the oar to push against the water on alternating sides, allowing for efficient and controlled movement through the water. Sculling can be performed with one or two oars, but the description specifically applies to the use of a single oar.