Pronunciation: (breth'lis),[key] —adj. 1. without breath or breathing with difficulty; gasping; panting: We were breathless after the steep climb. 2. with the breath held, as in suspense, astonishment, fear, or the like: breathless listeners of the mystery story. 3. causing loss of breath, as from excitement, anticipation, or tension: a breathless ride. 4. dead; lifeless.
5. motionless or still, as air without a breeze: a breathless summer day.