true north

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌtrue ˈnorth noun [uncountable]  PGnorth as it appears on maps, calculated as a line through the centre of the Earth rather than by using the magnetic pole 真北〔地图上的北方，即根据地球中轴线而不是磁极计算的正北方〕

Examples from the Corpus

true north• In the true north light he seemed much older.• Its north points to true north.

ˌtrue ˈnorth nounChineseSyllable  

maps, it calculated as Corpus on appears as north

true north
ˌtrue ˈnorth noun [uncountable]
north as it appears on maps, calculated as a line through the centre of the earth rather than by using the magnetic pole

true northBrE /ˌtruː ˈnɔːθ/ 🔊NAmE /ˌtruː ˈnɔːrθ/ 🔊 noun [uncountable] north according to the earth's axis (= the imaginary line through the earth's centre from north to south) 真北（以地轴北极为正北）  ➡  compare magnetic north