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

Turf has a serious image problem in Fort Lauderdale because of costly, blazing hot turf at a small park near the tunnel. —Steve Bousquet, Sun Sentinel, 6 June 2026

However, investing in public institutions and infrastructure is a costly endeavor that can seem unreasonable when local officials are struggling to balance budgets without increasing tax burdens. —Aneri Pattani, USA Today, 6 June 2026

Wembanyama committed a costly turnover and missed the final shot in Friday night’s 105-104 loss to the Knicks in Game 2 of the NBA Finals at the Frost Bank Center. —Peter Sblendorio, New York Daily News, 6 June 2026

None of these studies take into account homeowners who opt out only of the costly windstorm coverage specific to hurricane damage, but keep the less expensive general policy, which covers things like fire, theft and general liability. —Ashley Miznazi, Miami Herald, 6 June 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