V-ようものなら: meaning and usage

How to form it

• verb (volitional form)+ものなら
• verb (volitional form)+もんなら

How it is used

After the volitional form: if someone were to do A, something bad would follow, often as an exaggerated warning. Speech says 「〜ようもんなら」. After the potential form, 「〜ものなら」 means 'if only one could'.

Examples

1. 見た目だけで彼女を馬鹿にしようものなら、後々痛い目を見るよ。

   If you make fun of her only because of her appearance, you'll have trouble in the future.

2. うちの父は厳しくて、門限を一分でも過ぎようものなら大変なことになる。

   My father is strict: if I'm even a minute past curfew, there's big trouble.

3. この道は狭いので、大型バスが入ろうものなら、たちまち渋滞してしまう。

   This road is narrow; if a big bus were to come down it, traffic would jam in no time.