breathless

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Breathing with difficulty; gasping.
• adjective Excited or tense, often to the point of holding the breath.
• adjective Tense or exciting, often in causing or being characterized by holding of the breath.
• adjective Not breathing; without breath.
• adjective Dead.
• adjective Having no air or breeze; still.

from The Century Dictionary.

• Without breath; dead.
• Out of breath; spent with labor or exertion.
• That takes away the breath.
• Marked by an apparent forgetfulness to breathe; absorbed; eager; excited.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Spent with labor or violent action; out of breath.
• adjective Not breathing; holding the breath, on account of fear, expectation, or intense interest; attended with a holding of the breath.
• adjective Dead.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Having difficulty breathing; gasping.
• adjective That makes one hold one's breath (with excitement etc.).
• adjective Not breathing; apparently dead.
• adjective Having no wind; still, calm or airless.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective tending to cause suspension of regular breathing
• adjective appearing dead; not breathing or having no perceptible pulse
• adjective not breathing or able to breathe except with difficulty