true north
noun [ U ] uk/ˌtruː ˈnɔːθ/ us/ˌtruː ˈnɔːrθ/
真北（地球北极的方向，沿着一条想象的直线与赤道成90度）
the direction towards the top of the earth along an imaginary line at an angle of 90° to the equator
True north runs parallel to the earth's axis. 真北与地轴平行。