ignition

B2 · Upper Intermediate Countable noun

n. the part of a car or machine that starts the engine.

n. the electrical or mechanical system used to start a combustion engine, or the switch where the key is inserted.

“He turned the key in the ignition, but the car wouldn't start.”

“A malfunction in the electronic ignition prevented the spark plugs from firing, leaving the vehicle stranded in the middle of the highway.”

C2 · Proficiency Uncountable noun Science Technical

n. the point when a nuclear reaction becomes powerful enough to keep itself going.

n. the state in which a thermonuclear fusion reaction becomes self-sustaining, requiring no further external energy input.

“Scientists are working hard to achieve ignition in fusion energy experiments.”

“Achieving fusion ignition represents a major milestone in physics, as it produces more energy than the lasers used to start the reaction.”