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

And before signing up for any costly or invasive intervention, run it past your own physician — particularly stem cell treatments, aggressive IV protocols or anything sold as a cure or prevention for a specific disease. —Hanna Wickes, Miami Herald, 23 May 2026

Spirit Airlines cited costlier jet fuel when shuttering operations earlier this month. —Alex Harring, CNBC, 23 May 2026

Hydee Feldstein Soto’s first term was marked by an explosion in costly litigation against the city and allegations of misconduct and mistreatment of employees. —Sonja Sharp, Los Angeles Times, 23 May 2026

But there was immediate backlash with some residents wondering why only one vendor was considered for such a costly project. —Claire Wang, Oc Register, 23 May 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