The phrase "unprecedented precision" means that something is being done or measured with a level of accuracy and exactness that has never been seen or achieved before. Full definition
This well - known, but tiny effect was measured with unprecedented precision in 2010 using two optical clocks — however, they were located at the same institute. (sciencedaily.com)
As a result, they were able to obtain an angle - amplitude measurement of unprecedented precision, unbothered by quantum uncertainty. (sciencedaily.com)
Killeen notes that those programs will rely on unprecedented precision in measuring and monitoring greenhouse gas emissions, a role AGU scientists might fill. (scientificamerican.com)