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

The goal here is to reduce reliance on outside models, which can be costly. — Jeff Marks, CNBC, 7 July 2026

Moving fast and smart – as an efficiency first strategy enables – is the winner as compared to the more cumbersome and costly conventional approach. — Kathleen “katie” McGinty, Fortune, 6 July 2026

Goalkeeper Matt Freese’s costly blunder in the 57th minute was an embarrassment that gifted the Belgians a third goal to all but seal the elimination loss. — Miami Herald, 7 July 2026

Share a common taxonomy to ensure all stakeholders use the same language when discussing legal exposure, avoiding costly miscommunications. — Gaby Prechner, Forbes.com, 7 July 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