nebula

noun

neb·​u·​la ˈne-byə-lə 

plural nebulae ˈne-byə-ˌlē  -ˌlī  also nebulas

1

: any of numerous clouds of gas or dust in interstellar space

2

: galaxy sense 1b

especially : a galaxy other than the Milky Way galaxy

—not used technically

nebular

ˈne-byə-lər 

adjective

Did you know?

The history of nebula belongs not to the mists of time but to the mists of Latin: in that language nebula means "mist" or "cloud." In its earliest English uses in the 1600s, nebula was chiefly a medical term that could refer either to a cloudy formation in urine or to a cloudy speck or film on the eye. Nebula was first applied to great interstellar clouds of gas and dust in the early 1700s. The adjective nebulous comes from the same Latin root as nebula, and it is considerably older, being first used as a synonym of cloudy or foggy as early as the 1300s. Like nebula, this adjective was not used in an astronomical sense until centuries later.

Examples of nebula in a Sentence

Recent Examples on the Web

Astronomers suspect the nebula's formation was primarily driven by the more massive of the two stars. —Sharmila Kuthunur, Space.com, 15 Apr. 2025

The recent Hubble image, which was shared online on March 17, also captures a nebula that casts a hazy blue-greenish shadow over part of the star cluster. —Samantha Mathewson, Space.com, 31 Mar. 2025

Spiral starburst galaxy glows in gorgeous Hubble Telescope image Emission nebulas are areas of active star formation, where ultraviolet radiation from nearby young, hot stars ionizes the surrounding gas (primarily hydrogen), which then, in turn, emits a bright light. —Samantha Mathewson, Space.com, 21 Mar. 2025

These nebulae can also form after black holes swallow a star. —Joshua Rapp Learn, Discover Magazine, 25 Feb. 2025

Word History

Etymology

New Latin, from Latin, mist, cloud; akin to Old High German nebul fog, Greek nephelē, nephos cloud

First Known Use

1718, in the meaning defined at sense 1

Phrases Containing nebula

• planetary nebula

Podcast

Get Word of the Day delivered to your inbox!

Kids Definition

nebula

noun

neb·​u·​la ˈneb-yə-lə 

plural nebulas or nebulae -ˌlē 

-ˌlī

1

: any of many huge clouds of gas or dust in deep space

2

: galaxy sense 2

nebular

-lər 

adjective

Medical Definition

nebula

noun

neb·​u·​la ˈneb-yə-lə 

plural nebulas or nebulae -ˌlē  -ˌlī 

: a slight cloudy opacity of the cornea