second thought

American

Or second-thought

noun

Often second thoughts. reservation about a previous action, position, decision, judgment, or the like.

He had second thoughts about his decision.

idioms

on second thought, after reconsideration.

On second thought, I don't think I'll go.

second thought British

noun

(usually plural) a revised opinion or idea on a matter already considered

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of second thought

First recorded in 1625–35

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Cars, which we jump into every day without a second thought, are not as safe statistically.

From MarketWatch • Apr. 9, 2026

But on second thought, no one is better at playing The Entitled Mean Girl than Bondi herself.

From Los Angeles Times • Feb. 13, 2026

Because my routine screening hadn’t detected any abnormalities, I didn’t give it a second thought.

From Slate • Feb. 4, 2026

Then: "On second thought, I changed my mind."

From BBC • Dec. 13, 2025

A second thought always followed the first, one mystery bred another: Was everyone else really as alive as she was?

From "Atonement" by Ian McEwan

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023