testing

1. To challenge.

   Climbing the mountain tested our stamina.

2. To refine (gold, silver, etc.) in a test or cupel; to subject to cupellation.
3. To put to the proof; to prove the truth, genuineness, or quality of by experiment, or by some principle or standard; to try.

   to test the soundness of a principle; to test the validity of an argument

4. (academics) To administer or assign an examination, often given during the academic term, to (somebody).
5. To place a product or piece of equipment under everyday and/or extreme conditions and examine it for its durability, etc.
6. To be shown to be by test.

   He tested positive for cancer.

7. To examine or try, as by the use of some reagent.

   to test a solution by litmus paper

1. To attest (a document) legally, and date it.
2. To make a testament, or will.

noun

The act of conducting a test; trialing, proving.

adjective

Difficult, tough