a.

1. 貴重的，寶貴的
   costly jewels

   貴重的珠寶

2. 昂貴的；代價高的
   The general's decision to invade was a costly mistake.

   將軍作出的入侵決定是個代價慘重的錯誤。

   Your suggestion is feasible, though it might be rather costly.

   你的建議是可行的，但也許要付出不少代價。

3. 奢華的

adj.

1. expensive.
2. causing suffering, loss, or disadvantage.