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

The goal is to limit the amount of ratepayer money spent on costly infrastructure that the state hopes to phase out in the coming decades as part of its climate goals. —NPR, 13 Oct. 2025

Ward went 3-for-10 passing for just 15 yards and one costly interception – a pick that Wyoming’s Brayden Johnson returned 65 yards for a touchdown, bringing the Cowboys within 28-21 with 10 minutes to play. —Aaron Johnson, Mercury News, 13 Oct. 2025

Continue reading … CRIME MAGNET – Washington Post rips Democratic Socialist's costly bus proposal for New Yorkers. —FOXNews.com, 13 Oct. 2025

According to city records, the majority of citations are in the tens of thousands of dollars range, but three are upwards of $100,000 – with the costliest fine at $300,000. —Ryanne Mena, Oc Register, 13 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