distension in a plant cell caused by its fluid contents.

Merriam-Webster Online Dictionary
turgor (noun)
the normal state of and tension in living cells - turgidity , especially the distension of the protoplasmic layer and wall of a plant cell by the fluid contents
turgor (Wikipedia)

Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall.

It is also called hydrostatic pressure, and defined as the pressure measured by a fluid, measured at a certain point within itself when at equilibrium. Generally, turgor pressure is caused by the osmotic flow of water and occurs in plants, fungi, and bacteria. The phenomenon is also observed in protists that have cell walls. This system is not seen in animal cells, seeing how the absence of a cell wall would cause the cell to lyse when under too much pressure. The pressure exerted by the osmotic flow of water is called turgidity. It is caused by the osmotic flow of water through a selectively permeable membrane. Osmotic flow of water through a semipermeable membrane is when the water travels from an area with a low-solute concentration, to one with a higher-solute concentration. In plants, this entails the water moving from the low concentration solute outside the cell, into the cell's vacuole.

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