Sunday punch

American  

noun

1. Boxing. the most powerful and effective punch of a boxer, especially the punch used in trying to gain a knockout.

2. anything, as an armed force, line of argument, etc., capable of inflicting a powerful blow on a hostile or opposing person or thing.

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Sunday punch British  

noun

1. boxing a heavy blow intended to knock out one's opponent

2. any manoeuvre or action intended to crush an opponent

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Etymology

Origin of Sunday punch

First recorded in 1930–35

Example Sentences

The takeaway: During your driver fitting don’t just focus on the distance number you get with your Sunday punch.

From Golf Digest

We knew the syllogism was the conclusion, the Sunday punch.

From Project Gutenberg