[ kawst-lee, kost- ]
/ ˈkɔst li, ˈkɒst- /
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See synonyms for: costly / costlier / costliest / costliness on Thesaurus.com

adjective, cost·li·er, cost·li·est.
costing much; expensive; high in price: a costly emerald bracelet; costly medical care.
resulting in great expense: The upkeep of such a large house is costly.
resulting in great detriment: It was a costly mistake because no one ever trusted him again.
of great value; very valuable; sumptuous.
lavish; extravagant.
In effect, this quiz will prove whether or not you have the skills to know the difference between “affect” and “effect.”
Question 1 of 7
The rainy weather could not ________ my elated spirits on my graduation day.
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Origin of costly

First recorded in 1350–1400, costly is from the Middle English word costli. See cost, -ly

synonym study for costly

1. See expensive.


cost·li·ness, nouno·ver·cost·li·ness, nouno·ver·cost·ly, adjectiveun·cost·ly, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use costly in a sentence

  • In 112 extremely uncostly frames on the wall were the coffin-plates of the departed members of the family.

    Two Little Savages|Ernest Thompson Seton
  • They are uncostly, plain, and humble, showing the unostentatious mind of the great man.

  • Alas, they are homespuns from the factory, machine-made in uncostly quantities.

    The Rhythm of Life|Alice Meynell

British Dictionary definitions for costly

/ (ˈkɒstlɪ) /

adjective -lier or -liest
of great price or value; expensive
entailing great loss or sacrificea costly victory
splendid; lavish

Derived forms of costly

costliness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012