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

In the past, making deepfakes—a term created by a Reddit user in 2017 —was costly and time-consuming. —Matt Emma, USA Today, 3 Nov. 2025

But with fieldwork costly and orca hunts difficult to predict, gathering more data will take time. —Aamir Khollam, Interesting Engineering, 3 Nov. 2025

The pressure dialed up by Minnesota, along with costly penalties, put this offense in unfavorable spots throughout the game. —Colton Pouncy, New York Times, 3 Nov. 2025

She was struck by how intricately this costly brand was linked to her life and to her family’s finances. —Naomi Rougeau, Robb Report, 2 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