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

Incredibly costly, tapestries were a status symbol for the wealthy, notably, the nobility and royalty, and used in their public and private spaces, from dining and gathering rooms to bed chambers. —Kristina McGuirk, Better Homes & Gardens, 29 June 2025

Similarly, our transit system — the CTA, Pace and Metra — needs an overhaul, but not through costly projects like the $1 billion-per-mile Red Line expansion. —Chicago Tribune, 29 June 2025

In such situations, systematic errors are more costly. —Oliver Swainston, Space.com, 28 June 2025

Even so, many developers continue to argue that prevailing wage rates are still too costly to make construction pencil out beyond the state’s priciest metro areas, making those prior housing bills ineffective at actually producing more housing. —Ben Christopher, Mercury News, 27 June 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