adjective
Costing a lot of money.
The repair was costly.
They bought a costly new computer.
Common phrases & grammar
costly repair · costly purchase
a costly + noun
subject + be + costly
American English
How to pronounce costliest
adjectiveB2
KAWSTleeihst
/ˈkʰɔst̚.li.ɪst̚/
3 syllables · Stress the first syllable.
Related entry: costly
Costing a lot of money.
Practice out loudMeanings & examples
adjective
Causing a large loss of money, time, or other resources.
It was a costly mistake.
The delay proved costly for the company.
Good to know
For mistakes or delays, costly often means that they cause serious loss, not simply that they have a high price.
Common phrases & grammar
costly mistake · costly error
a costly + noun
subject + be + costly
Related words & forms
The y changes to i in costlier and costliest. You can also say more costly and most costly.