Rare literary word for keen intelligence and sound judgment. Not used in everyday conversation; more common synonyms include 賢明 or 聡明.
His sagacious decision saved the company.
The old man was known for his sagacity.
The kanji 聡 (wise, quick of perception) and 敏 (clever, agile) combine to suggest sharp intelligence. The exact historical derivation is uncertain, but the word is a Sino-Japanese compound.