depressomotor

from The Century Dictionary.

• Causing a retardation of motor activity.
• noun An agent which retards motor activity.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Med.) Depressing or diminishing the capacity for movement, as depressomotor nerves, which lower or inhibit muscular activity.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective medicine Depressing or diminishing the capacity for movement.
• noun medicine Any agent that depresses the activity of the motor centres.