In this sentence:

Iron melts at around 770 degrees Celsius, 1,400 degrees Fahrenheit.

What is the grammatical function of the words 'Celsius' and 'Fahrenheit' ?

  • 8
    It's effectively an adjective on "degrees". The order can be reversed if you wish, but the above order is "traditional".
    – Hot Licks
    Nov 20, 2015 at 12:43
  • 7
    @MJF But the terms degrees Celsius and Celsius degrees are used in different circumstances. It is 23 degrees Celsius outside. The temperature has fallen by five Celsius degrees since noon.
    – WS2
    Nov 20, 2015 at 13:20
  • 6
    @WS2: I don't recognise that distinction. So far as I'm concerned it's always postpositive (rise/fall/whatever) by two degrees Centigrade (about 160 hits in Google Books, whereas there are none at all for by two Centigrade degrees). It's like no-one ever talks about sterling pounds - our currency is always pounds sterling, regardless of the syntactic context. Nov 20, 2015 at 13:44
  • 2
    @FumbleFingers When reporting the temperature I would agree it is always degrees Celsius. But I think more latitude exists for such as Phew, what a scorcher! Apparently London is only two Celsius degrees lower than Singapore. Though I agree two degrees Celsius would work just as well.
    – WS2
    Nov 20, 2015 at 21:23
  • 3
    @FumbleFingers - in science and engineering, degrees Centigrade is a temperature and Centigrade degrees is a temperature difference. It's not at all uncommon, just outside many people's sphere of experience. Nov 21, 2015 at 16:47

3 Answers 3


They are called a "postpositive adjective".

"Celsius" is so defined in Oxford Online Dictionary:

[POSTPOSITIVE WHEN USED WITH A NUMERAL] Of or denoting a scale of temperature on which water freezes at 0° and boils at 100° under standard conditions: 'a temperature of less than 25° Celsius'


[POSTPOSITIVE WHEN USED WITH A NUMERAL] Of or denoting a scale of temperature on which water freezes at 32° and boils at 212° under standard conditions: 'the temperature was steady at 65° Fahrenheit'

They are put after "degrees" even though they are adjectives, which are usually placed before a noun.


The below Ngram Viewer shows a big difference in their usages.

Second Edit:

As suggested by @Edwin Ashworth, it could also be called a post-nominal noun modifier. The linked Wikipedia article about postpositive adjective has the below explanation:

In some phrases, a noun adjunct appears postpositively (rather than in the usual prepositive position). Examples include Knights Hospitaller, Knights Templar, man Friday (or girl Friday, etc.), airman first class (also private first class, sergeant first class), as well as many names of foods and dishes, such as Bananas Foster, beef Wellington, broccoli raab, Cherries Jubilee, Chicken Tetrazzini, Crêpe Suzette, Eggs Benedict, Oysters Rockefeller, peach Melba, steak tartare, and duck a l'orange.

Note: Oxford Online Dictionary, Merriam-Webster, Collins Online Dictionary, American Heritage® Dictionary of the English Language, Fifth Edition and Random House Kernerman Webster's College Dictionary, Dictionary.com all (six dictionaries) classify the word as an adjective while Wiktionary does as a noun.

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  • I know it sounds "bad" - but I guess you technically could say "65 Celsius degrees", since 'degree' is a unit of measurement no matter which system you are, and Celsius would just be qualifying which degrees you mean.
    – galois
    Nov 20, 2015 at 22:28
  • @jaska Yes, you could. And Ngram Viewe shows usages, but very low compared with postpositive usage.
    – user140086
    Nov 21, 2015 at 4:29
  • 1
    @jaska - and why scientists would say 138 kelvin, to avoid the problem
    – mgb
    Nov 21, 2015 at 5:12
  • And to find a more historical perspective on "Celsius", search "Centigrade" instead. When Celsius became the official term I'm not sure, but I only heard Centigrade (and Fahrenheit) in common use until sometime in the 1970s. Nov 21, 2015 at 13:38
  • -1 "Adjective" is the simple answer. That being postpositive is incidental.
    – Kris
    Nov 21, 2015 at 13:46

I disagree with previous responses. "Degrees celsius" is the unit, so we have a compound noun. Three rabbits, four horse radishes, five degrees celsius.


Yes, Celsius and Fahrenheit are adjectives in this example, with the function of making the unit of measurement more specific. Other similar usages with unambiguous adjectives -- "6 meters high", "5 meters deep", 3 items short", "5 inches wide", "10 years old".

  • Which of meters high maps tho Celsius ?
    – mmmmmm
    Nov 20, 2015 at 20:42
  • degrees Celsius -> meters high. in this, degrees maps to meters and Celsius to high. Nov 20, 2015 at 21:48
  • 3
    I don't think "Celsius" takes the same function as "high" in your example. You can ask "How high is it?", but you cannot ask "How Celsius is it?".
    – Emil
    Nov 20, 2015 at 23:14
  • It's more like the difference between avoirdupois and Troy when talking about ounces (weight). Degrees is the number of things, Celsius (or Fahrenheit) is the size and scale of the things you're talking about.
    – bye
    Nov 21, 2015 at 2:08
  • But you can use Celsius on its own (more often the absolute version Kelvin or Rankin) Celsius surely must map to meter here being the unit of measurement
    – mmmmmm
    Nov 22, 2015 at 14:11

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