Merriam-Webster defines superstition as:
1 a : a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation
b : an irrational abject attitude of mind toward the supernatural, nature, or God resulting from superstition
2 : a notion maintained despite evidence to the contrary
But there is another definition, put forward by old wives and rational, intelligent folk everywhere: