Concrete means specific and real, not vague or abstract. When your teacher asks for concrete examples to support your argument, she wants actual facts and details, not general statements. If you say “exercise is good for you,” that's abstract. If you say “running three times a week strengthens your heart and helps you sleep better,” that's concrete.

This connects to the other meaning of concrete: the hard building material made from cement, sand, gravel, and water. When wet concrete hardens, it becomes incredibly strong and durable. Cities are built with concrete: sidewalks, bridges, buildings, and roads. Ancient Romans invented an early version of concrete and used it to build structures like the Pantheon, which still stands in Rome today after nearly 2,000 years.

Both meanings share the idea of something solid and definite. Abstract ideas float around like clouds; concrete ideas and concrete structures both stay firmly in place. When you make your thinking more concrete, you give people something solid to understand and remember.