まさか

まさか
adverb
surely not, no way
1. surely not, no way, by no means
Expresses disbelief or denial that something could be true or happen.
合格(ごうかく)したよ」「まさか!」
"I passed!" "No way!"
Used as an interjection expressing disbelief
まさか(かれ)犯人(はんにん)だとは(おも)わなかった。
I never thought he could be the culprit.
まさかこんなことになるとは(おも)ってもいなかった。
I never dreamed things would turn out like this.
2. just in case, in the unlikely event
Used with の/に to mean 'in case of emergency' or 'for an unexpected situation.'
まさかの(とき)のために貯金(ちょきん)している。
I'm saving money for a rainy day.
まさかの(とき) = emergency, unexpected situation
まさかの事態(じたい)(そな)えて、非常食(ひじょうしょく)用意(ようい)しておいた。
I prepared emergency food in case of an unexpected situation.
まさかの場合(ばあい)は、この連絡先(れんらくさき)電話(でんわ)してください。
In the unlikely event of an emergency, please call this contact number.

USAGE PATTERNS:

  • まさか〜ないだろう (surely...won't)
  • まさか〜とは(おも)わなかった (never thought that...)
  • まさか! (No way! - as an exclamation)
  • まさかの(とき) (in case of emergency)
  • まさかの事態(じたい) (unexpected situation)

NUANCE:
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(ほんとう)だとは... (I never thought it was actually true...).