Define osmosis. Is it the passage of water from a dilute solution to more concentrated one through a semipermeable membrane?

Yes. Osmosis is the movement of solution towards a more concentrated solution through a semipermeable membrane. In other words, osmosis is the diffusion of water or other solvent molecules.

Solutions are made of a solvent and a solute. The solvent is the substance that does the dissolving. The solute is the item(s) that is/are dissolved. Some resources refer to solutions of different concentrations as hypertonic, hypotonic, or isotonic. The term “tonic” refers to the solute concentration on either side of the semipermeable membrane. The hypertonic solution has a higher (“hyper”= a lot) solute concentration and lower solvent concentration. Likewise, the hypotonic solution has a low solute concentration and a high solvent concentration (“hypo” = low). In an isotonic solution, there are equal amounts of solute(s) on either side of the semipermeable membrane. Just as in diffusion, water moves from an area of greater concentration of water to an area of lesser concentration of water. Thus, water moves from hypotonic solutions towards hypertonic solutions. If the solutions are isotonic, then the net movement of water through the semipermeable membrane will be equal on either side.