Interjection
Usually written in kana
1.  by no means;  never!;  well, I never!;  you don't say!;  certainly (not)
Adjective (の)
Noun
Usually written in kana
2.  something unexpected;  emergency
Archaic
Noun
Usually written in kana
3.  currently;  for the time being;  presently;  for now
Adverb
Adjective (の)
Obscure
Usually written in kana
4.  indeed;  really;  truly;  unexpectedly