overspeed
1 of 3noun
: speed greater than normal or rated speed
subjected to overspeeds 
Time
Timeoverspeed
2 of 3verb
transitive verb
: to cause (as an engine) to run at an excessive speed
intransitive verb
: to run at an excessive speed
overspeed
3 of 3adjective
: operated or operating at greater than normal or rated speed
Word History
Etymology
Noun and Adjective
over entry 3 + speed, noun
Verb
over entry 1 + speed, verb