adj.
Pronunciation: ' ko ̇ s(t)-l ē
Function: adjective
Inflected Form: cost · li · er ; -est
Date: 14th century
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>
– cost · li · ness noun