1
interjection (kandoushi)
by no means;never!;well, I never!;you don't say!;no way!
まさかもう彼が来たのではないでしょうね。
He hasn't come already, has he?
2
certainly (not);surely (not);hardly (expected)
with neg. verb
3
something unexpected;emergency
See also:
まさかの時 (まさかのとき)
4
indeed;really;truly;unexpectedly
See also:
本当に (ほんとうに)
5
(the) present;(the) here and now;situation at hand