What's the semantic field of 無奈? How does "helpless" semantically appertain to "but; however"?
Oxford Chinese Dictionary (2010) p 786.
ABC Chinese–English Comprehensive Dictionary (2003), p 1007.
[1]
Originally, 无 means "not existing" and 奈 means "to deal with" (mainly used in negative / interrogative / rhetorical sentences).
Combined, 无奈 describes the situation of being helpless, having no means.
For example, "今天下雨了。出于无奈，主办方取消了活动。" means "It rained today. The orgnizers had no means but to cancel the event."
[2]
The meaning of 无奈 extents to express the feeling under such helpless situations. "感到无奈" is commonly used, which means "to feel regret/pity/disappointed" (because of factors not under control).
For example, "活动因为下雨取消了，大家都（感觉）很无奈。" means "We are all upset because the event is canceled due to the rain."
[3]
Further, 无奈 can be used as a conjunction to describe a turning which brings the feeling of 无奈[2]. For example, "我们本想参加活动，无奈下雨，活动取消了。" means "We wanted to attend the event, but it rained and the event was canceled."
