second thought

American  

Or second-thought

noun

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

   He had second thoughts about his decision.

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idioms

1. on second thought, after reconsideration.

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

second thought British  

noun

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

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Etymology

Origin of second thought

First recorded in 1625–35

Example Sentences

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

From MarketWatch • Apr. 9, 2026

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

From Slate • Feb. 4, 2026

I didn’t give the building a second thought until my best friend and I started a little weekly newspaper we photocopied for 3½ cents a copy from a shop a few doors away.

From Los Angeles Times • Dec. 9, 2025

"It's like a second thought, but thanks," she responded, with a laugh.

From BBC • Dec. 4, 2025

I sketch the outline of his head and shoulders without a second thought and start in on his brain map.

From "It’s Kind of a Funny Story" by Ned Vizzini