noun
Historical military term for a field headquarters or the general staff, especially in pre-modern Japanese contexts. Rare in modern usage; mostly encountered in historical texts or set phrases like 帷幄上奏.
帷幄上奏は、軍の統帥に関する事項を天皇に直接上奏する制度だった。
The 帷幄上奏 was a system in which matters concerning military command were reported directly to the Emperor.
歴史小説で「帷幄」という言葉を見かけることがある。
You may come across the word 帷幄 in historical novels.
From Chinese 帷幄 (wéiwò), literally 'curtains and tent', referring to the enclosed space where military commanders planned operations. The Japanese reading いあく is the on'yomi. The term is now largely historical.