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

The Rose Bowl is seeking to enforce terms of a lease that runs through 2044, arguing taxpayers are backing costly renovations at UCLA’s request and the Bruins’ departure would cause irreparable harm. —Anthony Solorzano, Los Angeles Times, 9 Feb. 2026

But the final result was costly and Liverpool are up against it. —Phil Hay, New York Times, 9 Feb. 2026

Would the 75-80 total days have been far too costly? —Brian Davids, HollywoodReporter, 9 Feb. 2026

During a recent City Hall meeting, commissioners were told by staff that tunnel builders cannot give a true estimate of cost without conducting a costly geotechnical survey, also known as a subsurface investigation. —Susannah Bryan, Sun Sentinel, 9 Feb. 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