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

Steelers, Saints, Cardinals Sam Darnold was nearly perfect (28-of-34 passing for 341 yards and four touchdowns), but his one mistake was a costly interception late that set up the Bucs’ winning field goal. —Chad Graff, New York Times, 7 Oct. 2025

Late public school buses and needing to take care of an occasionally sick child, along with at capacity or costly child care centers, contributed to her precarious employment. —Elizabeth B. Kim, Cincinnati Enquirer, 6 Oct. 2025

The stark difference proved costly as the club finished 82-80 and outside of playoff contention. —Kansas City Star, 6 Oct. 2025

Manual clearing is frequently slow, costly, and may leave behind stumps and fragments that contribute to regrowth. —Jon Stojan, USA Today, 6 Oct. 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