Scullers' Pair is a term used to describe two rowers in a boat, each with a single oar. The term is derived from the word scull, which is an oar used for propelling a boat. The term ELS is an abbreviation for 'Equal Length Strokes', which is a technique used by scullers to ensure that both rowers are pulling with equal force. This technique is essential for the boat to move in a straight line.