Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The radioactive isotope of hydrogen also known as hydrogen-3. It contains two NEUTRONS and one PROTON in its nucleus and decays to produce low energy BETA PARTICLES.
Hydrogen-3,Hydrogen 3
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Water
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)