under the knife

Idioms  

1. Undergoing surgery, as in He was awake the entire time he was under the knife. The phrase is often put as go under the knife meaning “be operated on,” as in When do you go under the knife? Knife standing for “surgery” was first recorded in 1880.

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Example Sentences

He died of heart failure and acute pulmonary edema -- a condition where fluid accumulates in the lungs -- two weeks after going under the knife.

From Barron's • Apr. 14, 2026

I was on more than 10 different medications when I went under the knife.

From The Wall Street Journal • Feb. 11, 2026

The case managers said partners pushed surgeries and would give bonuses when clients went under the knife.

From Los Angeles Times • Dec. 31, 2025

Gone are the days when facelifts were reserved for the ageing wealthy - now an increasing number of younger people are opting to go under the knife.

From BBC • Oct. 10, 2025

When my doctor told me that I had a really bad deviated septum, it seemed like a good excuse to go under the knife.

From "Americanized" by Sara Saedi