an·ni·hi·la·tion 
(ə-nī′ə-lāshən)
(ə-nī′ə-lāshən)n.
1.
a. The act or process of annihilating.
b. The condition of having been annihilated; utter destruction.
2. Physics The phenomenon in which a particle and an antiparticle, such as an electron and a positron, meet and are converted to a combination of energy or energetic particles approximately equivalent to the sum of their masses.
- hydrogen chloride
- hydrogen cyanide
- hydrogen fluoride
- hydrogen iodide
- hydrogen ion
- hydrogenolysis
- hydrogenous
- hydrogen peroxide
- hydrogen sulfide
- hydrogeologic
- hydrogeological
- hydrogeologist
- hydrogeology
- hydrographer
- hydrographic
- hydrographically
- hydrography
- hydroid
- hydrokinetic
- hydrokinetical
- hydrokinetics
- hydrolase
- hydrologic
- hydrological
- hydrologically