Plural of Nebula

The Quick Answer

The plural of nebula is nebulae or nebulas.

The Plural of nebula

The plural of nebula is nebulae. The alternative plural nebulas is rare but still acceptable.

Most nebulae are of vast size; some are hundreds of light-years in diameter.
In 1715, Edmond Halley published a list of six nebulas.

The noun nebula has a Greek root, which is the derivation of the plural nebulae. Nebulas (which adheres to the standard rules for forming plurals) is also an accepted plural.

The table below shows the standard rules for forming the plurals of nouns in English.

Type	Example of Type	Forming the Plural	Plural
Most Nouns	nebula scythe	add s	nebulas scythes
Noun Ending s, sh, ch, x or z	box dress	add es	boxes dresses
Nouns ending [consonant] o	hero zero tomato	add either s or es (There are no rules for this - you have to know.)	heroes zeros tomatoes
Nouns ending [vowel] o	patio ratio	add s	patios ratios
Nouns ending [consonant] y	story penny	change the y to an i and add es	stories pennies
Nouns ending [vowel] y	donkey chimney	add s	donkeys chimneys
Nouns ending f or fe	dwarf hoof	ves and/or s (There are no rules - you have to know.)	dwarfs hooves or hoofs
Exceptions	man louse	some nouns undergo a vowel or letters change	men lice
More exceptions	salmon sheep	some nouns do not change at all	salmon sheep
Foreign rulings	nebula medium	some nouns adopt foreign rulings	nebulae media

Why Is There Confusion over the Plural of Nebula?

Confusion arises over the plural of nebula because its original plural form (nebulae) derives from Greek and native English speakers are drawn to nebulas, which adheres to the standard ruling for forming plurals.

Nebulae is by far the more common plural of the two. (See the difference in Google's Ngram Viewer.)

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