ground truth
n.— «Weather spotters provide what’s called “ground truth” to the National Weather Service and emergency weather management. “We’re needed because cloud-piercing Doppler radar is very good at helping the National Weather Service see what’s going on in the upper atmosphere, but it’s unable to detect what’s actually happening on the ground because of the curvature of the Earth.”» —“Volunteers track storms” by Debra Carr-Elsing Capital Times (Madison, Wisconsin) Oct. 26, 2006. (source: Double-Tongued Dictionary)
Further reading
It was a dark and stormy night. So begins the long and increasingly convoluted prose of Edwards Bulwer-Lytton’s best-known novel. Today the annual Bulwer-Lytton Contest asks contestants for fanciful first sentences that are similarly...
A Wisconsin wonders if anyone outside her family uses the word funsel, possibly spelled funcil, to denote “a single strand of leftover cobweb hanging from the ceiling.” That one may be all their own, but another word she asks about, gnurr, meaning...