Noun:

1. a set that is empty; a set with no members

nulla[计] 空的nulladj.无效的；无价值的；无效力的n.零；空vt.使无效null address空地址null valence零价null forming零点形成null fill in零值补偿null pointer空指针null setting调零装置nullity suit请求宣判婚姻无效的诉讼null subject空主语null ellipse点椭圆nullo flight无人驾驶飞行