'Perihelion' definitions:

Definition of 'perihelion'

(from WordNet)
noun
Periapsis in solar orbit; the point in the orbit of a planet or comet where it is nearest to the sun [ant: aphelion]

Definition of 'Perihelion'

From: GCIDE
  • Perihelion \Per`i*hel"ion\, Perihelium \Per`i*he"li*um\, n.; pl. Perihelia. [NL., fr. Gr. peri` about, near + "h`lios the sun.] (Astron.) That point of the orbit of a planet or comet which is nearest to the sun; -- opposed to aphelion. [1913 Webster]