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

In the end, Reid believed the Chiefs offense struggled most with penalties and turnovers in critical situations, along with a short-term, costly bout of receiver drops. —Jesse Newell, New York Times, 7 Jan. 2026

Investing in the right cosmetics can be costly, and applying them is often time-consuming, but that’s only half the battle. —Michelle Baricevic, InStyle, 6 Jan. 2026

Polls show that most Americans believe that lengthy prison terms, which are costly to taxpayers, should be reserved for violent and hardened repeat offenders. —Kevin Krause, Dallas Morning News, 6 Jan. 2026

Carbon—like reverse osmosis, which requires costly equipment—can indiscriminately strip out smaller molecules, removing color and flavor along with any suspect chemicals. —Nicola Twilley, New Yorker, 5 Jan. 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