The word “ritual” comes from the Latin language of Ancient Rome. There it meant the customs of society.
This word is cognate with the Sanskrit word “ṛta,” for “natural order.”
That word is in turn related to the word for a Sanskrit term for season, “ṛtū,” which signifies the regular, annual passage of seasons (hot and cold weather).
A Sanskrit word for ritual, “ṛti,” also implies the upholding of Dharma, the natural law of the universe.
So rituals, too, recur, and they are predictable because they follow the same pattern each time. And in Hindu-Buddhist tradition they must be performed to maintain the natural balance of the universe.