nebula

American  

[neb-yuh-luh] / ˈnɛb yə lə /

noun

plural

nebulae, nebulas

1. Astronomy.

   1. Also called diffuse nebula.  a cloud of interstellar gas and dust.

   2. (formerly) any celestial object that appears nebulous, hazy, or fuzzy, and extended in a telescope view.

2. Pathology.

   1. a faint opacity in the cornea.

   2. cloudiness in the urine.

3. any liquid medication prepared for use as a spray.

---

nebula British  

/ ˈnɛbjʊlə /

noun

1. astronomy a diffuse cloud of particles and gases (mainly hydrogen) that is visible either as a hazy patch of light (either an emission or a reflection nebula ) or an irregular dark region against a brighter background ( dark nebula ) Compare planetary nebula

2. pathol

   1. opacity of the cornea

   2. cloudiness of the urine

3. any substance for use in an atomizer spray

---

nebula Scientific  

/ nĕb′yə-lə /

plural

nebulae

1. A visible, thinly spread cloud of interstellar gas and dust. Some nebulae are the remnants of a supernova explosion, others are gravity-induced condensations of the gases in the interstellar medium which in certain cases may become a site for the formation of new stars. The term was formerly used of any hazy, seemingly cloudlike object, including what are now recognized as other galaxies beyond the Milky Way; it is restricted now to actual clouds of gas and dust within our own galaxy.

2. ◆ Nebulae are generally classified as bright or dark. Among the bright nebulae are cold clouds that reflect light from nearby stars (reflection nebulae) and hot, ionized clouds that glow with their own light (emission nebulae). Dark nebulae—cold clouds that absorb the passing light from background stars—are called absorption nebulae.

3. See more at star

---

nebula Cultural  

1. plur. nebulae In astronomy, a hazy patch of light visible in the sky. Some nebulae are clouds of gas within the Milky Way; others are distant galaxies.

---

Other Word Forms

• nebular adjective
• nonnebular adjective
• prenebular adjective

Etymology

Origin of nebula

First recorded in 1655–65; from Latin: “cloud, mist, vapor”; akin to German Nebel “fog, haze,” Greek nephélē “cloud,” Sanskrit nábha- “cloud, vapor”

Example Sentences

Called Nebula PMR 1, the object has a striking appearance that resembles a brain inside a transparent skull, which is why it has been nicknamed the "Exposed Cranium" nebula.

From Science Daily • Mar. 17, 2026

In certain scenarios, nearly half of the modeled particles transported newly created organic molecules from the broader protosolar nebula into Jupiter's circumplanetary disk, where they were incorporated into the growing moons with little chemical change.

From Science Daily • Mar. 1, 2026

And perfectly in time for Halloween, they captured a spooky, red-glowing nebula that looks just like a bat signal shining across the universe!

From Space Scoop • Oct. 31, 2025

Some were gaseous, star-forming regions, such as the Orion nebula, or M42 – the 42nd object in Messier’s catalog – while others were star clusters such as the Pleiades, or M45.

From Salon • Feb. 14, 2025

Every planetary nebula is a token of a star in extremis.

From "Cosmos" by Carl Sagan