- costing much; expensive; dear
- at the cost of great effort, damage, sacrifice, etc.: a costly victory
- magnificent; sumptuous
- Archaic lavish; extravagant
Origin of costlyME: see cost and -ly
- Of high price or value; expensive: costly jewelry.
- Entailing loss or sacrifice: a costly war.
(comparative costlier, superlative costliest)
Composition: cost + -ly