Webster's 1913 Dictionary
PERIASTRON
Per `i *as "tron, n. Etym: [NL. , fr. Gr. (Astron.)
Defn: That point, in the real or apparent orbit of one star revolving around another, at which the former is nearest to the latter.
New American Oxford Dictionary
periastron
per i as tron |ˌperēˈastrən ˌpɛriˈæstrən | ▶noun Astronomy the point nearest to a star in the path of a body orbiting that star. ORIGIN mid 19th cent.: from peri- ‘around ’ + Greek astron ‘star, ’ on the pattern of perigee and perihelion .
Oxford Dictionary
periastron
periastron |ˌpɛrɪˈastrən | ▶noun Astronomy the point nearest to a star in the path of a body orbiting that star. ORIGIN mid 19th cent.: from peri- ‘around ’ + Greek astron ‘star ’, on the pattern of perigee and perihelion .
Duden Dictionary
Periastron
Pe ri as t ron , Pe ri as tron Substantiv, Neutrum Astronomie , das Periastrum |Peri a stron |das Periastron; Genitiv: des Periastrons, Plural: die Periastren zu griechisch perí = um – herum, nahe bei und astḗr = Stern Punkt in der Bahn des Begleiters eines Doppelsterns, in dem dieser dem Hauptstern am nächsten liegt
The Wordsmith Dictionary