'Tonicity' definitions:

Definition of 'tonicity'

From: WordNet
noun
The elastic tension of living muscles, arteries, etc. that facilitate response to stimuli; "the doctor tested my tonicity" [syn: tonicity, tonus, tone] [ant: amyotonia, atonia, atonicity, atony]

Definition of 'Tonicity'

From: GCIDE
  • Tonicity \To*nic"i*ty\, n. (Physiol.) The state of healthy tension or partial contraction of muscle fibers while at rest; tone; tonus. [1913 Webster]