true as steel
(as) true as steel
1. Unwaveringly loyal, dependable, and trustworthy; having unquestionable moral principles. The financial accounts are in good hands with Mr. Thompson, here—he's the best in the industry, and as true as steel. She's the one person in the whole operation I'd consider true as steel, the only one I'd put such faith in.
2. Absolutely correct; not untrue in the slightest. They say that actions speak louder than words, and that's as true as steel when it comes to politics. A: "Is what he said correct, Tom?" B: "Yep—true as steel."
*true as steel
very loyal and dependable. (*Also: as ~.) Through all my troubles, my husband has been as true as steel. Pedro was a staunch friend, true as steel.