the organic circulation of carbon from the atmosphere into organisms and back again
a thermonuclear reaction in the interior of stars
an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds
an interval during which a recurring sequence of events occurs
a periodically repeated sequence of events
a series of poems or songs on the same theme
a single complete execution of a periodically repeated phenomenon
the unit of frequency; one hertz has a periodic interval of one second
cause to go through a recurring sequence
