costly

adjective

cost·​ly ˈkȯs(t)-lē 

costlier; costliest

1

a

: commanding a high price especially because of intrinsic worth

costly gems

b

: rich, splendid

2

: made or done at heavy expense or sacrifice

a costly mistake

costliness noun

Synonyms of costly

• expensive
• valuable

Examples of costly in a Sentence

We use less costly materials in our products.

It was too costly to fix her car after the accident, so she decided to buy a new car instead.

They won the game, but their best player was injured, so it was a costly victory.

The decision to wait could be a costly mistake.

Recent Examples on the Web

That revision found that a cost-effective diet was 21% more costly than previously assessed, so SNAP benefits experienced a big boost. —Zach Halaschak, The Washington Examiner, 24 Nov. 2025

Michigan was where Dutcher spent nine years, eight under Steve Fisher before Fisher was fired amid allegations that a booster paid players, an ironic twist when the current Wolverines roster ranks among the costliest in the nation at somewhere north of $12 million (for 13 scholarship players). —Mark Zeigler, San Diego Union-Tribune, 24 Nov. 2025

At present, the licensed treatment is a costly (£375,000 per year), weekly, lifelong Enzyme Replacement Therapy (ERT) called Elaprase. —Mrigakshi Dixit, Interesting Engineering, 24 Nov. 2025

Worker turnover is high across the industry, and everyone is trying to balance the costly infant rooms with more profitable ones for older children. —Lauren Hilgers, Harpers Magazine, 23 Nov. 2025

Word History

First Known Use

14th century, in the meaning defined at sense 1a

Kids Definition

costly

adjective

cost·​ly ˈkȯs(t)-lē 

costlier; costliest

1

: of great cost or value

costly furs

2

: gained at great expense or sacrifice

a costly victory

costliness noun