keystone

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

She pointed to the 1967 Outer Space Treaty, a keystone document on international space law that President Lyndon Johnson signed onto.

From Salon • Apr. 9, 2026

Last year, some 1,000 U.S. troops withdrew from neighboring Niger, ending a nearly decadelong partnership that was the keystone of U.S. counterterrorism operations in the region.

From The Wall Street Journal • Nov. 2, 2025

They "play a central role in the food web, consuming fish and invertebrates and recycling nutrients" and are one of the "keystone species" of their ecosystem.

From Barron's • Oct. 10, 2025

Despite the pile-up of particulars, Metcalfe knows he must find the lost poem, that it is the keystone without which the story crumbles into insignificance.

From Los Angeles Times • Sep. 19, 2025

Standing under the narrow arch I glanced up, wondering if that keystone too was mortared with bone and blood.

From "The Left Hand of Darkness" by Ursula K. Le Guin