(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.

plural of nuclear hydrogen detection meter

an atomic clock which uses the 1.4 GHz transition in a hydrogen atom to measure time to within 0.45 nanoseconds over a span of 12 hours

plural of hydrogen maser atomic clock

(chemistry) the cleavage of a molecule, especially that of a carbon-carbon bond, with the addition of hydrogen atoms to the fragments

(transitive, British spelling, dated) Alternative spelling of hydrogenize

(obsolete, chemistry) Hydrogen, especially when formerly considered as a metal.

(obsolete, chemistry) hydrogenated; hydrogenized

(obsolete, chemistry) Containing or producing hydrogen

plural of hydrogenosome