The term 'Steed Stopper' refers to a person who works with horses, and the two crossword solutions for this term are REIN and WHOA. The word REIN is a noun that refers to the straps or lines used to control a horse, while WHOA is an interjection used to tell a horse to stop. Therefore, the term 'Steed Stopper' can be used to describe someone who works with horses, such as a jockey, horse trainer, or stable hand, who uses reins and commands like 'WHOA' to control the horse.