a.

1. 贵重的，宝贵的
   costly jewels

   贵重的珠宝

2. 昂贵的；代价高的
   The general's decision to invade was a costly mistake.

   将军作出的入侵决定是个代价惨重的错误。

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

   你的建议是可行的，但也许要付出不少代价。

3. 奢华的

adj.

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