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

That could prove very costly — not to mention Paramount must pay a $7 billion regulatory termination fee if antitrust authorities halt the deal. —David Zimmermann, The Washington Examiner, 13 Apr. 2026

Utilities retired costly old plants in droves, replacing them with more efficient natural gas and renewables. —Matthew Brown, Los Angeles Times, 13 Apr. 2026

But with Charlotte winning, the Heat’s victory had no tangible benefit but could prove to be a bit costly from a draft standpoint. —Barry Jackson, Miami Herald, 13 Apr. 2026

Avoid costly financial moves Planning ahead for financial setbacks reduces the likelihood that you’ll be forced into making a suboptimal decision. —Jason Stauffer, CNBC, 13 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