What is meant by the term osmosis?

The net diffusion of water from an area of high concentration to low concentration across a partially-permeable membrane. 3 key elements to the definition1) Diffusion of water2) high conc to low conc3) partially permeable membrane Assess understanding of diffusion before explaining this. Reinforce the idea that this is simply a special name for diffusion of water through a semi-permeable membrane. Like diffusion, it is a passive process that does not require energy. Diffusion can be described through the idea of dropping some milk into a cup of tea and watching it spread out slowly. Osmosis occurs it rains in a desert and moves into the roots of a cactus.