1
: a unit of length in astronomy equal to the distance that light travels in one year in a vacuum or about 5.88 trillion miles (9.46 trillion kilometers)
2
: an extremely large measure of comparison (as of distance, time, or quality)
seems like light-years ago
has light-years more talent
two minutes and yet light-years away from the crowded village—
Suzanne Patterson
Suzanne PattersonExamples of light-year in a Sentence
my sister and I are close in age, but personality-wise, there are light-years between us
Recent Examples on the Web
At distances of around 10 billion light-years, the luminosity distance differs by more than a factor of two from the naive prediction.
—Big Think, 1 May 2026
Space is the massive, ever-expanding realm beyond Earth’s atmosphere, spanning more than 93 billion light-years in the observable universe.
—Georgina Jedikovska, Interesting Engineering, 27 Apr. 2026
The Trifid Nebula is a bright, colorful cloud of gas and dust about 5,000 light-years from Earth in the constellation Sagittarius, according to NASA.
—Eric Lagatta, USA Today, 27 Apr. 2026
Astronomers can use telescopes to find specific molecules in the atmospheres of neighboring planets, in nebulae – clouds of interstellar dust and gas – hundreds or thousands of light-years away, or in galaxies beyond the far reaches of the Milky Way.
—Olivia Harper Wilkins, The Conversation, 27 Apr. 2026
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Big Think, 1 May 2026
Space is the massive, ever-expanding realm beyond Earth’s atmosphere, spanning more than 93 billion light-years in the observable universe.
—Georgina Jedikovska, Interesting Engineering, 27 Apr. 2026
The Trifid Nebula is a bright, colorful cloud of gas and dust about 5,000 light-years from Earth in the constellation Sagittarius, according to NASA.
—Eric Lagatta, USA Today, 27 Apr. 2026
Astronomers can use telescopes to find specific molecules in the atmospheres of neighboring planets, in nebulae – clouds of interstellar dust and gas – hundreds or thousands of light-years away, or in galaxies beyond the far reaches of the Milky Way.
—Olivia Harper Wilkins, The Conversation, 27 Apr. 2026
See All Example Sentences for light-year
Cite this Entry
“Light-year.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/light-year. Accessed 5 May. 2026.
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