The word hypotonic originates from a Greek word where, hypo indicates under and tonos means tension. It is related to the tonicity of the solution, where the tonicity degree is quite low and the osmotic pressure is less than the other solution. Such a solution is said to by hypotonic.
The solute concentration is quite minimal when it is matched with the other solutions. The tonicity of a hypotonic solution is minimal when examined with the other solutions.
There will be a flow of water through the cell membrane due to variation in the tonicities of the solution. An example is when the blood serum is hypotonic against a particular solution, all the water molecule will move towards the place which has lower concentration of water.
In muscles which is hypertonic will have niftier tonicity or tension, whereas hypotonic muscle will have less tension and tonicity. Muscle is said to be isotonic when the tonicity is stable.