tonicity

noun

1. tonic quality or condition.
2. the state of bodily tone.
3. Physiology. the normal elastic tension of living muscles, arteries, etc., by which the tone of the system is maintained.

noun

1. the state, condition, or quality of being tonic
2. physiol another name for tonus

n.

1. Normal firmness or functional readiness in body tissues or organs.
2. The sustained partial contraction of resting or relaxed muscles.
3. The osmotic pressure or tension of a solution, usually relative to that of blood.