The best result data among many experiments with uncontrolled variations.

(idiomatic) To show resolve or effectiveness in dealing with a difficulty.

plural of champagne problem

Alternative form of yank someone's chain

plural of challenge exam

An examination that assesses a person's existing knowledge rather than coming at the end of a taught course.

A coin or medallion bearing an organization's emblem and carried by members to prove membership if challenged.

plural of challenge coin

An item of exercise equipment that supports the body during exercise of the lower back and sometimes the gluteal muscles, hamstring, and abdominals.

plural of chain drive