/ Dictionary / Index O oxygen cycle: Meaning and Definition of Find definitions for: ox'ygen cy"cle Pronunciation: [key] — Ecol. Ecol. the process by which oxygen released into the atmosphere by photosynthetic organisms is taken up by aerobic organisms while the carbon dioxide released as a by-product of repiration is taken up for photosynthesis. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. oxygenate oxygen debt Related Content Daily Word Quiz: morose Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language