A hypertonic environment is a solution in which the number of solutes is greater than the number of solvent, or concentration of solute is greater outside of a cell than inside of a cell.
The environment outside the vesicle is said to be hypertonic as the concentration of solute is greater outside the lipids vesicle, while the concentration of water or solvent is greater inside the lipids vesicle.
The interior of the lipid vesicle is hypotonic to the hypertonic surroundings, meaning the water flows out of the vesicle.
