• WordNet 3.6
    • adj heliacal pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun "the heliacal rising of the Dog Star","the heliacal or Sothic year is determined by the heliacal rising of Sothis (the Egyptian name for the Dog Star)"
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Webster's Revised Unabridged Dictionary
    • a Heliacal (Astron) Emerging from the light of the sun, or passing into it; rising or setting at the same, or nearly the same, time as the sun.☞ The heliacal rising of a star is when, after being in conjunction with the sun, and invisible, it emerges from the light so as to be visible in the morning before sunrising. On the contrary, the heliacal setting of a star is when the sun approaches conjunction so near as to render the star invisible.
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Century Dictionary and Cyclopedia
    • heliacal In old astronomy and chronology, near the sun: applied to those risings and settings of a star which were as nearly coincident with those of the sun as they could be observed. The stars rise and set a little earlier each successive day. The first rising of a star each year in time to be seen before sunrise is the heliacal rising; its last observable setting after sunset is the heliacal setting. From the time of a star's heliacal setting to that of its heliacal rising it is too near the sun to be seen at all—a period of 30 or 40 days, according to the reckoning of the ancients.
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Chambers's Twentieth Century Dictionary
    • adj Heliacal he-lī′ak-al (astron.) emerging from the light of the sun or passing into it
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Webster's Revised Unabridged Dictionary
Gr. belonging to the sun, fr. the sun: cf. F. héliaque,
Chambers's Twentieth Century Dictionary
Gr. hēliakoshēlios, the sun.


In literature:

They also possessed lists of the fixed stars, and drew up tables of the times of their heliacal risings.
"The Babylonian Legends of the Creation" by British Museum
We recognize to-day this "heliacal rising" of the stars.
"The Astronomy of the Bible" by E. Walter Maunder
Implying hereby the Heliacal ascent and Cosmical descent of those stars.
"The Works of Sir Thomas Browne (Volume 2 of 3)" by Thomas Browne