Measurement of the OSMOLARITY of solutions or BODY FLUIDS.

Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.

The pressure required to prevent the passage of solvent through a semipermeable membrane that separates a pure solvent from a solution of the solvent and solute or that separates different concentrations of a solution. It is proportional to the osmolality of the solution.

The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.