(roofing) A device that contains a radioactive source to emit high velocity neutrons into a roof system. Reflecting neutrons are measured by a gauge that is used to detect hydrogen; the quantity of hydrogen detected may be linked to the pressure of water.

(health sciences) The hygienic measures concerning a person's bodily condition, notably external cleanliness.

The concern and care for a clean, or healthy state of mind.

A word derived from etyma in two or more source languages; especially a word combining both Latin and Ancient Greek elements, such as quadrilogy, oscilloscope, or automobile.

a measure of the average length of time that a soluble compound remains in a constructed reactor

plural of hydraulic retention time

Alternative spelling of nonhydrodynamic

(mineralogy) A form of opal.

(hydraulics, surface science) For a porous material, the ratio of porosity (ratio of volume of interstitial space filled with fluid to volume of material) to specific surface area (ratio of surface area in contact with fluid to volume of material); for a pipe or channel, the ratio of cross-sectional area to wetted perimeter.

(neologism) Warfare that blends conventional warfare and irregular warfare (potentially including cyberwarfare and information warfare) — the full spectrum of conflict.