nebula: [17] As its form suggests, nebula was originally a Latin word, but it goes back to a prehistoric Indo-European base (*nebh- ‘cloud’) which produced a wide range of other descendants, including German nebel ‘cloud’, Greek néphos ‘cloud’, and Latvian debess ‘sky’. It also got into Old English, as nifol ‘dark’. The Latin word was originally used in English for a sort of ‘cataract’ over the eye, and the presentday astronomical application to a ‘cloud’ of stars did not emerge until the early 18th century. The derivative nebulous [16] is an earlier borrowing.
