noun-modifying (irregular)
unusual; extraordinary; alarming
Prenominal adjective describing something that is not ordinary, often with a nuance of seriousness or alarm. Commonly used in phrases like ただならぬ気配 (an unusual atmosphere) or ただならぬ事態 (an extraordinary situation).
部屋に入ると、ただならぬ雰囲気を感じた。
When I entered the room, I sensed an unusual atmosphere.
彼のただならぬ様子に、何かあったのかと心配になった。
His extraordinary demeanor made me worry that something had happened.