I am writing a piece on integration of differential equations. One of the words that I have to use frequently is "timestep" (however it is written), i.e. a step forward in the "simulated" time.

There seem to be three variants:

  • "time step"
  • "timestep"
  • "time-step"

The wikipedia article one Verlet integration in fact uses all three (!) of these variants.

Is there a context in which one is preferred over the other? How do I decide which one to use?

  • It doesn't seem to be included in major online dictionaries not requiring a subscription. I'd say that the compound noun is in its infancy, and there's often no consensus on whether to use one or other of the three possible (open, hyphenated and closed) forms. As a premodifier, I'd not use the open form, and I wouldn't be inconsistent (except where hyphenating a premodifier but using an open form otherwise). Otherwise, I'd say you're free to choose. – Edwin Ashworth Aug 31 '15 at 9:38
  • If you follow the links at the bottom of this Google ngram page, you will see that all three occur in published works. For some reason time-step and time step appear in the same category. I think you have to choose one and stick with it. books.google.com/ngrams/… – chasly - supports Monica Aug 31 '15 at 9:45
  • purely as a vote, I'd say "time-stamp" is best. – Fattie Aug 31 '15 at 11:48
  • I think "interval" is the term you're looking for. – Hot Licks Aug 31 '15 at 12:09
  • I think you can use all three variants. I would use time step. – rogermue Aug 31 '15 at 14:56

A general remark on hyphens from Longman English Grammar by Aleander

1 There are no precise rules.

2 When short nouns are joined together, they form one word without a hyphen (a teacup). But this may lead to problems of recognition, therefore bus stop, not busstop.

3 Hyphens are often used for verb + particle combinations as in make-up.

4 When a compound is accepted as a single word, i.e. it has an entry in a dictionary, the tendency is to write it as one word (sunbathing).

5 In other cases the use of the hyphen is at the discretion of the writer, writing paper or writing-paper.

6 But the tendency is to avoid hyphens where possible.


As I was writing this reply, the spellchecker flags timestep as not a word, so based on that I'd avoid it. Whether you need the hyphen or not depends on your usage. If you're using it as a compound adjective, it needs a hyphen; e.x. time-step methods for solving differential equations. The words time and step describe the method together so you hyphenate. If you're using it to describe a discreet interval of time, it does not; e.x. the first time step uses a forward difference, while subsequent time steps use the central difference method. Google "compound adjectives" for more explanation.

  • Note that timestep is no longer flagged as an error by the spellchecker. – Darryl Oct 28 '20 at 18:54

When I google "derivative timestep," I get many entries for "time step," but I don't get any with "timestep" on the first page. I do get "time-step," once.

Googling "derivative timestamp" gives a different set of pages, which are not about calculus but about web forum management and such (checking timestamps on posts that are "derivative"). This confirms what I know about the word "timestamp":

a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second" (Wikipedia).

A timestamp marks when something happened; a time step is the interval between two times.

So I would use "time step" (because it's most common) or possible "time-step," and consider "timestamp" to be an error.

  • If one is determined to use some variation of "time stamp", and not, say, "interval". – Hot Licks Oct 30 '15 at 23:31
  • 1
    timestamp came in through the comments and not from the OP; I think that confuses the question instead of clearing things up (unless that is just autocorrect being its usual helpful self). – NadjaCS Oct 30 '15 at 23:52
  • Yes, timestamp and timestep are very different concepts. – Darryl Oct 28 '20 at 18:42

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