noun
Rare, literary, or historical term for gunpowder. In modern Japanese, 火薬 (かやく) is the standard word.
煙硝の匂いが戦場に漂っていた。
The smell of gunpowder hung over the battlefield.
Standard modern word for gunpowder and explosives. 煙硝 is a rare, literary synonym.
The kanji 煙 (smoke) and 硝 (saltpeter) together suggest 'smoke-producing saltpeter', a descriptive term for gunpowder. The reading えんしょう is on'yomi. The exact historical derivation is uncertain.