形容詞 breathless:

1. not breathing or able to breathe except with difficulty
   同義詞：dyspneic, dyspnoeic, dyspneal, dyspnoeal
2. tending to cause suspension of regular breathing
   同義詞：breathtaking
3. appearing dead; not breathing or having no perceptible pulse
   同義詞：inanimate, pulseless

1. The children are breathless as they watch the tightrope act.
   孩子們在看走繩索表演時(shí)呼吸都屏住了。
2. A breathless audience.
   屏住呼吸的觀眾
3. I met him in a hot and breathless afternoon.
   我是在一個(gè)又悶又熱的下午遇到他的。
4. I was completely breathless when I got to the top of the mountain.
   當(dāng)我到達(dá)山頂上時(shí)，我已經(jīng)上氣不接下氣了。

breath.less

adj.（形容詞）
Breathing with difficulty; gasping:
呼吸困難的；氣喘吁吁的：
例句：
was breathless from running.
跑得上氣不接下氣的

Marked by the suspension of regular breathing, as from tension or excitement:
屏息的：以正常呼吸暫停為特點(diǎn)的，如出于緊張或激動：
例句：
a breathless audience.
屏住呼吸的觀眾

Causing or capable of causing the suspension of regular breathing; tense or exciting:
透不過氣的：使或能使正常呼暫停的；緊張的或扣人心弦的：
例句：
a breathless flight.
令人喘不過氣的飛行

Not breathing; without breath.
不呼吸的；沒有呼吸的
Dead.
死的
Having no air or breeze; still:
無風(fēng)而沉悶的：沒有空氣或微風(fēng)的；靜止的：
例句：
a breathless summer day.
一個(gè)無風(fēng)且沉悶的夏日

【引伸】
breath.lessly
adv.（副詞）
breath.lessness
n.（名詞）