The phrase "important cornerstone" means a crucial and fundamental part of something, like a building, that provides support and stability. Full definition
One of the most important cornerstones of strong and healthy relationships is trust. (novusmindfullife.com)
But the most important cornerstone for further genetic analyses has been laid.» (sciencedaily.com)
One of the most important cornerstones of our business: whether it hails from Britain or South America, we ethically source all of our high quality yarn from specialist mills who operate under the fair trade code of conduct. (plumoflondon.com)