Exceptionally strong or resistant: a cast-iron stomach. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "cast-iron" in a sentence
"It looked raw—walls and floors of big planks whitewashed clean, the railwood furniture, knots and grains left intact, the row of butter churns, the cast-iron range, big enough to feed the boys and all of their friends, and hers."
"The sauce was just a can of tomato paste mixed with water and sautéed garlic, all simmered in a big cast-iron pan."
"It was a virtuoso performance; he knew his little kitchen so well that he moved around it with the economy and grace of a dancer, sliding a drawer shut with his left hip while opening the refrigerator with his right hand, then swirling sizzling butter in a cast-iron pan with an expert flick of his wrist."