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

Despite dominating in nearly every category, Alabama made a series of errors which proved costly. —Chantz Martin, FOXNews.com, 16 Nov. 2025

Leaving a trip early can be costly due to airline and hotel cancellation or change fees. —Christopher Elliott, USA Today, 16 Nov. 2025

George Washington, who commanded the Americans, often made costly mistakes, and soldiers frequently went months without pay or proper food and clothing — even as they were exposed to the elements or the deadly smallpox. —Aramide Tinubu, Variety, 16 Nov. 2025

When talks broke down last month, YouTube TV said Disney was proposing costly terms that would lead to higher prices for and fewer choices for its subscribers. —Jason Ma, Fortune, 15 Nov. 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