costly

1 of 2

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

costliness

2 of 2

noun

cost·​li·​ness

ˈkȯs(t)-lē-nəs also ˈkäs(t)-

plural -es

: the quality or state of being costly : high price or value : expensiveness

Synonyms of costly

Adjective

• expensive
• valuable

Examples of costly in a Sentence

Adjective

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

Adjective

Supporters say the measure will speed up environmental review for certain projects, from affordable apartments to hospitals, cutting costly delays and passing those savings on to consumers. — Lila Seidman, Los Angeles Times, 1 Oct. 2026

What our study does offer is a much faster way to test combinations of assumptions that are too costly to simulate one by one. — Robert Kopp, The Conversation, 30 Sep. 2026

Codified in 1969, those more stringent and costly restrictions have guided—and greatly limited, some critics say—Mars exploration ever since. — Joseph Howlett, Scientific American, 30 Sep. 2026

The governments of the Dominican Republic, Nicaragua, and several small Caribbean countries have subsidized energy costs—a costly proposition as high prices persist. — Dan Restrepo, Foreign Affairs, 30 Sep. 2026

Word History

First Known Use

Adjective

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