imaginary number
noun
: a complex number (such as 2 + 3i) in which the coefficient of the imaginary unit is not zero
called also imaginary
compare pure imaginaryExamples of imaginary number in a Sentence
Recent Examples on the Web
There are also what are known as imaginary numbers like i, which is the square root of –1, and complex numbers, which are sums of real and imaginary numbers.
—
Kenneth Chang, New York Times, 26 Mar. 2025
This means they are made of both real numbers and the imaginary number i: the square root of negative 1.
—William Ross, The Conversation, 10 Mar. 2025
Other rings of integers can be built out of sets of numbers that include, say, the square root of −1 (the imaginary number that mathematicians call i), or the cube root of 2.
—Joseph Howlett, WIRED, 9 Mar. 2025
There’s imaginary numbers and abstract theoretical math.
—The Editors, JSTOR Daily, 24 Jan. 2024
Advanced students learn about the complex numbers, which are formed by combining the real numbers and imaginary numbers; for instance, i=√−1.
—Quanta Magazine, 27 June 2023
Eventually, the parts of the photon’s behavior described by the imaginary numbers will correspond to actual measurable properties.
—Jackie Appel, Popular Mechanics, 10 June 2023
Physicist Richard Feynman once predicted that number 137 defines the table’s outer limit; adding any more protons would produce an energy that could be quantified only by an imaginary number, rendering element 138 and higher impossible.
—Rebecca Coffey, Discover Magazine, 29 Nov. 2011
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Kenneth Chang, New York Times, 26 Mar. 2025
This means they are made of both real numbers and the imaginary number i: the square root of negative 1.
—William Ross, The Conversation, 10 Mar. 2025
Other rings of integers can be built out of sets of numbers that include, say, the square root of −1 (the imaginary number that mathematicians call i), or the cube root of 2.
—Joseph Howlett, WIRED, 9 Mar. 2025
There’s imaginary numbers and abstract theoretical math.
—The Editors, JSTOR Daily, 24 Jan. 2024
Advanced students learn about the complex numbers, which are formed by combining the real numbers and imaginary numbers; for instance, i=√−1.
—Quanta Magazine, 27 June 2023
Eventually, the parts of the photon’s behavior described by the imaginary numbers will correspond to actual measurable properties.
—Jackie Appel, Popular Mechanics, 10 June 2023
Physicist Richard Feynman once predicted that number 137 defines the table’s outer limit; adding any more protons would produce an energy that could be quantified only by an imaginary number, rendering element 138 and higher impossible.
—Rebecca Coffey, Discover Magazine, 29 Nov. 2011
Cite this Entry
“Imaginary number.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/imaginary%20number. Accessed 31 Oct. 2025.
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