1.
surely not, no way, by no means
Expresses disbelief or denial that something could be true or happen.
2.
just in case, in the unlikely event
Used with の/に to mean 'in case of emergency' or 'for an unexpected situation.'
Common patterns
- まさか〜ないだろう (surely...won't)
- まさか〜とは思わなかった (never thought that...)
- まさか！ (No way! - as an exclamation)
- まさかの時 (in case of emergency)
- まさかの事態 (unexpected situation)
Usage
まさか conveys strong doubt or disbelief. When something actually happens that you thought was impossible, you might say まさか本当だとは... (I never thought it was actually true...).