Meaning of know one's onions | Babel Free

Definitions

Synonym of know one's stuff, to be knowledgeable about a given subject or task.

informal

Examples

“Joe really knows his onions when it comes to cooking.”

“Sam Tyler: Well, our first priority is to make sure the thieves don't strike again. It'll be tricky, 'cause these sorts of gangs rarely have just one target on the go. They've usually researched half a dozen possibilities, waiting for the most opportune circumstances on any of them. Harry Woolf: He knows his onions, this lad, eh? Gene Hunt: Oh, he's a right little smart-arse. So, what do you suggest, Buddha?”

CEFR level