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

Turns out the independent expenditure campaigns in the race are nearly as costly. —Los Angeles Times, 2 May 2026

Schwarzman went big on costly, stylish architecture and great living conditions. —Shawn Tully, Fortune, 2 May 2026

At the same time, climate change, housing costs, aging infrastructure, and income inequality have made the baseline conditions of life in California riskier and costlier. —Ben Allen, Oc Register, 2 May 2026

Yet another costly stream to watch. —Ticked Off, The Orlando Sentinel, 2 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