堅硬:
1. hard
2. solid
Relative explainations:
<flintiness> <indurate> <rigidness> <rigidity> <stiffness> <solidity> <solidness> <adamancy> <adamant> <rocklike> <hardness> <rigid> <steel>
Examples:
1. 黑檀樹是一種黑色而堅硬的樹木。