Water closet
Water closet means a plumbing fixture that has a water-containing receptor which receives liquid and solid body waste, and upon actuation, conveys the waste through an exposed integral trap seal into a gravity drainage system, except such term does not include fixtures designed for installation in prisons.
Source
10 CFR § 430.2
Scoping language
For purposes of this part, words shall be defined as provided for in section 321 of the Act and as follows -