Nouns

(n)overridea manually operated device to correct the operation of an automatic device
(n)nullification, overridethe act of nullifying; making null and void; counteracting or overriding the effect or force of something

Verbs

(v)overrule, overturn, override, overthrow, reverserule against“The Republicans were overruled when the House voted on the bill”
(v)overrideprevail over“health considerations override financial concerns”
(v)overridecounteract the normal operation of (an automatic gear shift in a vehicle)
(v)overrideride (a horse) too hard