timekeeper

In 1967, the world's timekeepers, an intergovernmental body called the General Conference on Weights and Measures, agreed to define time using atomic clocks, rather than by the Earth's rotation.

On one level, a main timekeeper, head judge and team leader scrutinize footage from the main camera.

Scientists use tiny minerals called zircons as geologic timekeepers.

The effect is that global timekeepers may need to subtract a second from our clocks later than would otherwise have been the case.

This question of how to situate our time in the narrative arc of Earth history has thrust the rarefied world of geological timekeepers into an unfamiliar limelight.