costly

B2 Topic:Describing Qualities

US /ˈkɑːstli/ UK /ˈkɒst.li/ See IPA manual

Freq #14721

Meanings

1

adj
Costing a lot of money; expensive.

Repairing the old roof turned out to be a costly job.
2

adj
Causing serious loss, harm, or sacrifice.

Ignoring the warning signs proved to be a costly mistake.

Thesaurus

Synonyms

1 adj · costing a lot of money;... dear expensivehigh-pricedpricey

2 adj · causing serious loss, harm,... dearly-won

Opposites

costlessly

Word family

Forms costliercostliest

Appears in

Phrases (1)

See all

costly mistake
an error that results in a significant loss or disadvantage

Adjective + noun

Etymology

From Middle English costly, costely, costeley, equivalent to cost + -ly.

costly Middle English

View etymology graph ->

Topics

Describing Qualities

External links

# costly

**Type:** Word
**Level:** B2
**Part of speech:** adj
**IPA (US):** /ˈkɑːstli/
**IPA (UK):** /ˈkɒst.li/
**Frequency rank:** 14721

## Meanings
1. Costing a lot of money; expensive.
2. Causing serious loss, harm, or sacrifice.

## Examples
- Repairing the old roof turned out to be a costly job.
- Ignoring the warning signs proved to be a costly mistake.

## Antonyms
- costlessly

## Roots and Affixes
- Root: costly

## Etymology
From Middle English costly, costely, costeley, equivalent to cost + -ly.

## AI Etymology
Costly is from Middle English costly, costely, costeley, equivalent to cost plus -ly. The suffix -ly recasts equivalent to cost as an adverb: the lexical idea remains recognizable, but the word now describes manner, degree, or circumstance rather than naming the quality by itself. In use as an adjective, costly denotes costing a lot of money; expensive and causing serious loss, harm, or sacrifice. Typical contexts include “Repairing the old roof turned out to be a costly job” and “Ignoring the warning signs proved to be a costly mistake”.

## Topics
- Describing Qualities

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