Something that's crushed is broken or crumbled into small pieces, or crumpled so that it's very wrinkled. Crushed ice is one way to chill your lemonade on a hot day.
You can use crushed stone to pave the paths in your garden, or add crushed garlic to spice up your soup. It's less pleasant to see your car's crushed fender after an accident, or to end up with a crushed toe after accidentally dropping a brick on your foot. A figurative way to be crushed is to be completely devastated or humiliated: "She had a crushed expression on her face after losing the spelling bee."