spasticity

https://doi.org/10.1351/goldbook.12083
Increased muscle tone at rest, characterized by resistance to passive stretch.
Note: Increased deep tendon reflexes and clonus are additional manifestations.
Source:
PAC, 2015, 87, 841. (IUPAC Glossary of terms used in neurotoxicology (IUPAC Recommendations 2015)) on page 906 [Terms] [Paper]