Idiom
know one's onions
Meanings
To be highly knowledgeable or skilled in a particular area; to be an expert.
Definition
To know one's onions means to be very knowledgeable and competent about a particular subject or job.
If you know one's onions, you understand a topic or task very well and can handle it confidently. It is often used to praise someone’s expertise or practical skill. The phrase is informal and common in British English, but it is understood in many other varieties of English.
Examples
- Ask Priya about taxes—she really knows her onions.
- Our new project manager knows his onions and keeps everything on track.
- If you want solid advice on hiking gear, Jordan knows his onions.
- The consultant clearly knows her onions; the results improved within weeks.
More at C1 level
- Monday morning quarterback A “Monday morning quarterback” is someone who criticizes decisions after the outcome is already kno…
- close but no cigar Used to say someone almost succeeded but did not quite achieve the goal.
- come hell or high water No matter what happens or how difficult things become.
- brass monkeys “Brass monkeys” is used in the expression “cold enough to freeze the balls off a brass monkey,” mea…
- get down to brass tacks To get down to brass tacks means to start discussing the most important practical details of someth…
More idioms
- Bob's your uncle Used to say that something will be easy or will happen exactly as expected after a simple step.
- close but no cigar Used to say someone almost succeeded but did not quite achieve the goal.
- down to the wire If something goes down to the wire, it is decided at the very last moment before the deadline or fi…
- lost the plot To become confused or unreasonable and no longer understand what is happening or what matters.
- ducks in a row To have everything organized and ready in the correct order.