The type of passive transport that involves the movement of water across a semipermeable membrane from a region of high water concentration to a region of low water concentration is called what?

This type of passive transportation is called OSMOSIS.
Osmosis is a type of passive transportation in which a liquid moves from the region of high concentration to the region of low concentration. The movement usually continues until the amount of liquid on both sides are the same. This type of movement does not require energy because the flow is naturally favored, that is, molecules moves from high end to low end.