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

Mayfield also threw a costly interception late in the fourth quarter, which all but sealed the game for the Eagles. —James Brizuela, MSNBC Newsweek, 29 Sep. 2025

Forest were on course to secure a comfortable win at Swansea City in the Carabao Cup before conceding costly late goals. —Paul Taylor, New York Times, 29 Sep. 2025

The Indianapolis Colts, another unbeaten team heading into Week 4, were left to rue Adonai Mitchell’s costly error in their 27-20 loss to the Rams at SoFi Stadium. —George Ramsay, CNN Money, 29 Sep. 2025

Carbon capture challenges Hiegel explained that carbon capture remains hindered by high energy demands, poor flexibility with industrial loads, costly infrastructure requirements, and health and safety risks from degrading chemicals, all of which slow its adaptability. —Georgina Jedikovska, Interesting Engineering, 29 Sep. 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