柯林斯词典air sac 1. N any of the membranous air-filled extensions of the lungs of birds, which increase the efficiency of gaseous exchange in the lungs (鳥類的)氣囊 返回 air sac剑桥词典a space filled with air that continues from a bird's lungs into one of its bones or another body area , used in breathing 氣囊（鳥類躰內從肺部延伸至骨骼以及其他身躰部分的氣囊，用於呼吸） a wide part like a bag in the tubes an insect uses for breathing （崑蟲的）氣囊 an alveolus (= a very small air bag in the lungs ) 肺泡 返回 air sac