paratonic
/ˌparəˈtɒnɪk/adjective
1 Medicine. Of or relating to strain or spasm (of muscle); specifically designating muscle rigidity occurring in response to passive movement, seen in various disorders of the cerebral cortex.
2Originally: designating or relating to movements of plants in response to change in the intensity of light; nyctinastic. Later: designating plant movements caused by external stimuli of any kind.
Origin
Mid 19th century; earliest use found in Robert Mayne (1808–1868). From para- + tonic.