1. something that settles a matter; a decisive blow or answer
Usage: informal; archaic
2. something outstanding or exceptional
Usage: informal; archaic

Examples

• His final argument was a real sockdolager that won the debate.
• The prosecutor delivered a sockdolager that left the defense speechless.
• That storm last night was a sockdolager – I’ve never seen rain like that.
• Her performance in the final act was a sockdolager that brought the audience to their feet.
• The team’s comeback victory was a sockdolager that no one saw coming.