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

In the context of life valuation, the VSL framework leads regulators to prioritize costly measures that current individuals happen to favor, even if those resources could save more lives (or otherwise enhance welfare more) if allocated differently. —James Broughel, Forbes.com, 27 Jan. 2026

Billions lost to fraud and broken oversight The analysis reveals that some of California's most costly cases of fraud or untracked spending were the subjects of numerous prior audits. —Julie Watts, CBS News, 27 Jan. 2026

And Caruso likely saw a costly, but extremely narrow, path to victory. —Matt Fleming, Oc Register, 26 Jan. 2026

Usually, space saver incidents are less violent, but still costly. —Colleen Cronin, Boston Herald, 26 Jan. 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