You are watching: Is nighttime one word or two
I did check the dictionary before posting yet a dictionary can"t tell me around real-life usage frequencies.
I originally closevoted v a comment speak the general trend is to move from two separate words, through the hyphenated form to a single-word form. Yet actually it"s a little bit more complex than that. Compare this NGram for what i would contact a "compound noun" intake at nighttime...
...with the much more obviously "compound adjective" intake a nighttime
What you see at first glance is that the "noun" consumption has declined all at once (we"ve increasingly tended to discard words time in constructions prefer "Dracula visited her in ~ night). ~ above the other hand, we"ve end up being increasingly fond of the compound adjectival form.
But if you look an ext closely, you"ll notice that return the single-word kind has end up being the most common in both contexts, there"s to be a far-ranging shift in relative choices for the other two forms. Together a "noun", the double-word kind is now slightly desired over the hyphenated one, however as one "adjective" the opposite preference is currently quite marked.
In light of that i think I must qualify my original comment. The general propensity is certainly to discard the hyphen - however whereas "compound adjective" usages invariably replace it v a single-word form, in various other contexts we"re quite likely to revert come a two-word form.
This same difference can be viewed if we compare adjectival fleabitten (where the hyphenated kind continues to dominate) v the noun fleabite (where the two-word kind is currently preferred).
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I think what this method is that writers in basic increasingly disapprove "indiscriminate" usage of hyphenated develops (just as we no longer indulge in the indiscriminate capitalisation the C19 and also earlier). Yet hyphenated compound adjectives are much more resistant to this change than other usages. Due to the fact that we don"t prefer two-word compound adjectival develops at all, we store the hyphen uneven the single-word kind is both acquainted (to the ear) and easy come parse (for the eye).