dropout
A person who quits school or a program before finishing.
A dropout is someone who leaves school, college, or a program before finishing it. When students drop out, they stop attending classes and don't complete their degree or diploma.
Dropping out of high school can mean limited job opportunities and lower earnings over a lifetime. Some famous entrepreneurs like Steve Jobs and Bill Gates dropped out of college (not high school) to pursue their business ideas, though this is quite rare and they had already developed valuable skills.
The word can describe other situations too. An athlete might drop out of a race due to injury, or a candidate might drop out of an election when they realize they won't win.
People sometimes use dropout as an adjective, like “dropout rates,” to discuss what percentage of students leave school early.