While looking up nebulous, I noticed the origin of the word is dating back to 14th century. Surprised since the nebulae wasn't discovered at that time, I checked nebula to find that its origin dates to 17th century. Given nebulous means nebula-like, it seems inconsistent that it enters the dictionary before its derivative.

It's obvious that nebula with its Greek/Latin root existed long before 17th century. But could nebulous have been used without nebula not even being mentioned for 3 centuries?

Am I missing a point? Or is the dictionary wrong?

Or should we take these as non-definitive dates which just represent the first written occurrence of the word?

nebulous: 1375 - 1425 Late Middle English)
nebula: 1655-65 < Latin

  • This question is nebulous!
    – Thursagen
    May 31, 2011 at 7:10
  • Don't be such a nebbish, Third
    – JeffSahol
    May 31, 2011 at 12:14

4 Answers 4


These words come from Latin nebula. Both nebula and nebulosus ("nebulous") existed in classical Latin. In the Middle Ages, anyone who could write was likely to know Latin.

That is why writers freely borrowed such Latin and French words as they saw fit: it is very well possible that the English derivation of nebulosus was used before that of nebula. However, that doesn't tell us much, because no doubt those writers knew both Latin words and had both in mind. Latin and English together formed a large mass (or mess) from which a writer could take any word he needed, Latin being used mostly where an English word was lacking, or where a high register was desired.

In addition, I believe the word nebula was first borrowed as nebule, attested from ca. 1420, according to the Oxford English Dictionary. Note that nebule originally just meant cloud, fog, mist—nothing specifically scientific. It is used figuratively here:

c1420 Lydg. Commend. Our Lady 53 O ... Light withoute nebule, shyning in thy spere.

This comes quite close to the earliest attested date for nebulous, ca. 1386:

c1386 Almanack (1812) 8 A thyk tyme, þat es for to say nebulus and cloudy.

Though by no means necessary, it is also very well possible that nebule was used in English writing some time before nebulous/nebulus but in a lost document.

  • this is a fine answer!
    – gpr
    Jul 26, 2016 at 1:11

They both came from two different Latin roots nebula or nebulosus.

Nebula was a noun, and meant "fog, mist, cloud"

Nebulosus was an adjective, and meant "foggy, cloudy, full of mist"

It was just that one word got invented earlier than the other because there was occasion for invention. For example, there were, I am sure, cases of confusion or vaguness long before, but diffusion nebulae were only discovered in the 17th century, hence the lateness for the invention of the word.


Many English words that end -ous have Latin counterparts that end -osus.

nebulous could have been a coinage directly from Latin nebulosus rather than via nebula.


The point you are missing is that "nebula" meant "cloud", or "fog" long before somebody discovered bright patches in the sky and cast about for a word to call them.

The word's origin goes back to Indo-European, and it is related, for example, to Russian "nebo" = "sky".

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