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

Western leaders largely dismissed these overt signals, assuming Putin would not be reckless enough to risk crippling sanctions, economic isolation, and a costly war. —Big Think, 20 Oct. 2025

In March 2023, a Washington State Supreme Court decided to uphold a 7% tax on capital gains, which would have become increasingly costly for Bezos. —Sydney Lake, Fortune, 20 Oct. 2025

Cost is still an issue As interesting as this news is, solid-state batteries are still very costly to produce, which is a major issue. —Christopher McFadden, Interesting Engineering, 19 Oct. 2025

Most costly for Rattler was a second-quarter interception on a pass over the middle to wide receiver Mason Tipton. —The Athletic Nfl Staff, New York Times, 19 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