arcanum ar-KAY-nuhm, noun;
plural arcana -nuh:

1. A secret; a mystery.

2. Specialized or mysterious knowledge, language, or information that is not accessible to the average person (generally used in the plural).

Arcanum is from the Latin, from arcanus “closed, secret,” from arca, “chest, box,” from arcere, “to shut in.”

debridement di-BREED-ment, day-noun

Surgical removal of dead, infected tissue or foreign matter from a wound.

From French debridement, from debrider (to unbridle), from Middle French desbrider (de- + brider).