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

• 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

His last walk of the night — four straight balls to Wilmer Flores — proved costly, preceding Chapman’s home run to extend the Giants’ lead. —Meghan Montemurro, Chicago Tribune, 27 Aug. 2025

Typically, rocket heat shields require extensive and costly refurbishment or wholesale replacement after flights. —Ruxandra Iordache, CNBC, 27 Aug. 2025

Still, turnovers proved costly, as Chicago gave the ball away 18 times, leading to 18 Aces points. —Grant Afseth, MSNBC Newsweek, 26 Aug. 2025

Such missteps can prove quite costly in an unforgiving playoff format where winning ensures advancement to the next round. —Jeff Gluck, New York Times, 25 Aug. 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