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

Patching up an outdated, aging infrastructure — like decades-old HVAC, electrical systems and leaking roofs — is a costly, short-term fix that drains our resources and ends up costing the community more. — Daily Southtown, Chicago Tribune, 22 Oct. 2026

While not all lawsuits filed against small businesses are valid, even an unsuccessful lawsuit can cause major business disruptions and result in costly legal fees. — Kaitlyn Gomez, Miami Herald, 22 Oct. 2026

Returning to the table, Walzer said that a legal scholar had recently used the jus ex bello doctrine in an op-ed to argue that the war had become so costly to Ukrainians that their government was now obliged to make concessions to stop the fighting. — Jordi Graupera, New Yorker, 22 Oct. 2026

Several situations can turn an otherwise promising credit card debt payoff strategy into a costly mistake. — Angelica Leicht, CBS News, 22 Oct. 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