Robust means strong, healthy, and able to withstand difficult conditions. A robust tree can survive harsh winters and summer droughts without losing its leaves or dying. A robust engine keeps running reliably even after years of hard use.

When scientists test a new invention, they want to make sure it's robust: that it works consistently in the real world where things get messy, not just once under perfect conditions. A robust bridge can handle heavy trucks, strong winds, and decades of weather. A robust business plan doesn't fall apart when unexpected problems arise.

People can be robust too. A robust elderly person stays active and healthy despite their age. The word suggests strength combined with durability, resilience, and the ability to keep going when things get tough. A robust debate means a vigorous exchange of ideas where people challenge each other respectfully.

The opposite of robust is fragile or delicate. A robust backpack survives being tossed around, stepped on, and stuffed full of books. A fragile one tears after a few weeks. When engineers say their design is robust, they mean it won't break easily or fail when conditions aren't perfect.