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

Maxey scored a game-high 31 points on 12-of-31 shooting, but Game 2 standout VJ Edgecombe struggled for the Sixers, going 5-for-17 and 0-for-7 from three with two costly fourth-quarter turnovers. —Zack Cox, Boston Herald, 25 Apr. 2026

That seems to have been the case at Cherry Creek Schools, and the board’s failure is a costly lesson for taxpayers. —Dp Opinion, Denver Post, 25 Apr. 2026

One challenge the next state controller will face is the effort to modernize the state’s payroll system, which has encountered significant delays and is one of California’s most costly IT projects. —William Melhado, Sacbee.com, 25 Apr. 2026

In Langesfeld’s case, Oscar Health repeatedly declined to cover the costly cancer-fighting drug therapy, arguing that the prescribed drug was not medically necessary or federally approved to treat his type of cancer. —Michelle Marchante, Miami Herald, 25 Apr. 2026

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