The term for the movement of water across a semipermeable membrane is called osmosis. This process occurs when water molecules move from an area of lower solute concentration to an area of higher solute concentration, aiming to achieve equilibrium. Osmosis is essential for maintaining proper cellular function in living organisms, as it influences cell turgor pressure and nutrient uptake. It plays a significant role in physiological processes such as filtration in the kidneys and nutrient absorption in the intestines.