This means "if you dare to do something." It shows that a very bad thing will happen if you do it.
Verb [volitional form] + ものならPrimary
This means "if you dare to do something." It shows that a very bad thing will happen if you do it.
父はとても厳しいので、門限を1分でも破ろうものなら、一週間は口をきいてもらえない。
My father is very strict, so if I were to break curfew by even one minute, he wouldn't speak to me for a week.
あんな危険な場所へ一人で行こうものなら、命がいくつあっても足りない。
If you were to go to such a dangerous place alone, any number of lives wouldn't be enough.
祖父の時代は、親の言うことに少しでも逆らおうものなら、勘当されたそうだ。
In my grandfather's time, I hear that if you were to even slightly disobey your parents, you would be disowned.
この精密機械は、素人が下手にいじろうものなら、すぐに壊れてしまうだろう。
If an amateur were to carelessly tamper with this precision machine, it would probably break immediately.
彼はプライドが高いから、人前で恥をかかせようものなら、二度と口を利いてくれないだろう。
He has a lot of pride, so if you were to make him lose face in public, he probably wouldn't ever speak to you again.
This grammar is like a warning sign. It only talks about bad things that could happen. It's never used for good or neutral results. It often sounds like a complaint.
This grammar is different from '〜たら'. '〜たら' just means 'if'. This grammar means 'if you dare to do something bad'. It always warns of a very bad result. It is like saying 'if you do this, something terrible will happen'.
Watch out: Do not use this pattern for good things. For example, do not say, "If it is sunny tomorrow, let's go for a picnic." This grammar is for bad things that probably will not happen. Or it makes a situation sound very bad.
Don't use this when you want to give an order. For example, you cannot say "If you are late, please apologize."
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