/ Dictionary / Index P perihelion: Meaning and Definition of Find definitions for: per•i•he•li•on Pronunciation: (per"u-hē'lē-un, -hēl'yun), [key] — pl. -he•li•a the point in the orbit of a planet or comet at which it is nearest to the sun. Cf.See diag. under Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: perihelion (Thesaurus) perigyny perikaryon Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language