Strong's G931 — βάσανος (noun)
basanos (bas'-an-os) n.
1. a touchstone used to test the purity of gold
2. (generally) a test to prove the genuineness of a thing
3. (figuratively) an instrument used in questioning by which one is compelled to divulge the truth
4. (by analogy) torture
[perhaps remotely from baino "to walk", through the notion of going to the bottom]
KJV: torment 
See also: G939 
Occurrences: 3