perihelion

UK: /ˌpɛrɪˈhiːlɪən/

US: /ˌpɛrəˈhiliən, -ˈhiljən/

US: (per′ə hē′lē ən, -hēl′yən)

Inflections of 'perihelion' (n): npl: perihelia

WordReference Random House Learner's Dictionary of American English © 2025

per•i•he•li•on /ˌpɛrəˈhiliən, -ˈhilyən/   n. [countable] , pl. -he•li•a 

/-ˈhiliə, -ˈhilyə/.  
1. Astronomy the point in the orbit of a planet or comet at which it is nearest to the sun.Compare aphelion.

See -helio-.

WordReference Random House Unabridged Dictionary of American English © 2025

per•i•he•li•on  (per′ə hē′lē ən, -hēl′yən), n., pl. -he•li•a (-hē′lē ə, -hēl′yə). [Astron.]

1. Astronomy the point in the orbit of a planet or comet at which it is nearest to the sun. Cf. aphelion. See diag. under aphelion. 

• Greek peri- peri- + hé̄li(os) sun + -on neuter noun, nominal suffix, on the model of perigee; earlier in the Neo-Latin form perihelium
• 1660–70

per′i•he′li•al, per′i•he′li•an, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

perihelion / ˌpɛrɪˈhiːlɪən/ noun ( -lia / -lɪə/)

1. the point in its orbit when a planet or comet is nearest the sun
   Compare aphelion

Etymology: 17th Century: from New Latin perihēlium, from peri- + Greek hēlios sun