SI unit
noun [ C ] science specialized uk/ˌesˈaɪ ˌjuː.nɪt/ us/ˌesˈaɪ ˌjuː.nɪt/
国际标准单位
a unit of measurement that is part of a system used for scientific and technical work all over the world
The SI unit of length is the metre. 长度的国际标准单位是米。