The term in(-)situ visualization denotes a visualization or graphics that is depicted in place, for instance, a sparkline that is embedded into text.

As the dictionaries tell, the adjective or adverb in situ is written as two words. But for concatenated terms in scientific language, oftentimes, in-situ (with a hyphen) is placed in front of the main noun. Searching for the term in Google and Google Scholar, I find both alternatives about equally frequent. Also, the COCA Corpus lists both versions for related terms such as in(-)situ burning.

What is the correct spelling of in(-)situ visualization? Is there a specific rule that applies?

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    No hyphen needed. It is a foreign phrase (?'borrowed phrase') with a specific meaning. The same form of the phrase can be used for all purposes. Use of the hyphen is a scholarly hypercorrection, I believe. – Kris Jul 1 '13 at 12:44
  • You should write visualization in situ as if it were Latin and/or English rather than, say, German. – Anton Sherwood Jun 15 '20 at 1:46

No hyphen needed.

In situ (adverb & adjective) is a Latin phrase (?'borrowed phrase') with a specific meaning. The same form of the phrase can be used for all purposes.

Use of the hyphen is a scholarly hypercorrection, I believe.

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    Why "scholarly"? Wouldn't scholars be less likely to indulge in hypercorrection than the unschooled? The practice is by definition associated with thinking one knows more than one actually does. – dodgethesteamroller Jul 9 '13 at 4:22

I agree with the lengthy reply provided by @dodgethesteamroller that ended with "Thus "in situ visualization" is unambiguous because "in situ" cannot be mistaken for two separate adjectives; there is no such thing as "situ visualization." It's fine to put the hyphen in, but it may be perceived as old-fashioned by some copyeditors."

However, I would take it one step further to drive home the importance of the rule that usage be guided by "meaning clarification". Here's a simple rule: "If italicizing, then no hyphen. If not italicizing, then hyphenate." Either method avoids confusion in phrases like “in in vitro experiments” The double "in in" is not uncommon in scientific writing. Using both italics and hyphen is overkill and a good example of hypercorrection.


This is the type of question that can easily be answered by referring to a dictionary. Dictionaries are much better than search engines for this type of question. Search engines only tell you what is there, i.e. what others have used - be it right or wrong. Dictionaries tell you what is right.

Chambers and ODO (Oxford) both give "in situ" (two words) for use as adjectives or adverbs, in British usage. American usage may differ - use an American dictionary if that is what you require.

[Following added after Question was modified]

Personally, I see no problem with hyphenating in-situ when used as an adjective or adverb, and indeed, it may be considered as making it clearer. It is not unusual to hyphenate compound adjectives: whether or not to is more a matter of style, clarity, and common usage. It is not really a matter of which is right or wrong.

But, "in situ" is two words and I think it may be considered incorrect to write it as one un-hyphenated word. I certainly wouldn't do so.

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    This is true, the dictionaries list in situ (without a hyphen) as an adjective/adverb, also the American ones. But still, as Google Scholar and the COCA corpus confirm, it is frequently used with a hyphen in front of nouns for established terms in scientific language. So, why? Is there any rule that applies or is it just an error? I did not find the answer in the dictionary. – fbeck Jul 1 '13 at 10:55
  • I extended the question with respect to what dictionaries tell. – fbeck Jul 1 '13 at 11:07
  • And I've extended the answer! – TrevorD Jul 1 '13 at 11:54

The key here is not whether or not in situ is properly spelled as two words (it is) nor what its part of speech is (it can be an adjective or adverb). The question is whether it should be hyphenated when used as an adjective directly before a noun. You're not finding an explanation in the dictionary simply because it's a matter more appropriate to a style or usage handbook.

Hyphens in compound adjectives, up until the latter part of the twentieth century, were considered mandatory. Modern usage, however, is to use them only to clarify meaning. Sometimes the need for such clarification is quite subtle:

  • Wikipedia gives an excellent example of "white-hot metal" vs. "white hot metal." In the former, "white-hot" is a particular state of the heating of the metal; it describes metal heated to the point where it turns white. In the latter, "white" and "hot" are given equal weight when describing the metal; it is white, and it is hot, but the former word is not semantically modifying the latter.

  • Homer's Odyssey contains a noun phrase famously translated as "wine-dark seas." Here the hyphen is necessary because "wine" alone cannot be an adjective, but in combination with "seas" alone it could conceivably be taken as a noun phrase with a different meaning: "wine seas" could be a slightly strange way to refer to "vast quantities of wine." But this is not what the poet and the translator meant: rather, "wine-dark" is an adjective invented especially for the situation, a compound meaning "as dark as wine." (I was taught in grade school to interpret such expressions as answering questions from the inside out: What is being described? Seas. What kind of seas where they? Dark seas. What kind of dark seas? Wine-dark seas, as dark as wine.)

Thus "in situ visualization" is unambiguous because "in situ" cannot be mistaken for two separate adjectives; there is no such thing as "situ visualization." It's fine to put the hyphen in, but it may be perceived as old-fashioned by some copyeditors.

  • 2
    Except that "in situ" is not a compound adjective, but rather a Latin prepositional phrase being used as an adjective, just like "in vitro" and "in utero," which I have also never, for the life of me, seen hyphenated. – Branimir Ćaćić Jul 2 '13 at 2:10
  • @BranimirĆaćić According to the definition of "compound adjective" given on Wikipedia, it's both. And Google will show you plenty of examples of "in-vitro" and "in-utero" before nouns. – dodgethesteamroller Jul 2 '13 at 15:08
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    "Thus 'in situ visualization' is unambiguous because 'in situ' cannot be mistaken for two separate adjectives; there is no such thing as 'situ visualization.'" It is unambiguous if the reader is familiar with the relatively uncommon term in situ. If not, "situ visualization" may seem to be the more appropriate reading in many contexts, which would send the reader on a wild goose chase for a definition that doesn't exist. I would use the hyphen. – phenry Jul 2 '13 at 16:28
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    First time I've had an answer of mine simultaneously accepted as correct and downvoted below zero. I don't know what to make of that... – dodgethesteamroller Jul 2 '13 at 17:49
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    @phenry It has been the custom to italicize foreign words: "in situ visualization" -- that too helps recognize the phrase as a unit. – Kris Jul 3 '13 at 5:06

My PhD is in English, but I spend a lot of time providing writing support for PhD scientists at universities and national laboratories. The case of in situ was one of the first real grammatical conundrums that I encountered, and I was boggled by the sheer variety of published permutations. (One well-respected scientist told me very seriously that the phrase should be either italicized or hyphenated, but not both. This was apparently advice that she had received from her graduate advisor.)

I understand the theory, but English is a continually-evolving language. (If enough people use a phrase "incorrectly" then it eventually becomes "correct" by popular consensus.) Realistically, there are different grammatical trends that have emerged within certain scientific sub-fields.

My practical advice to scientists who want to publish in a particular journal is to go to the journal's website, do a quick search for "in situ," and see how the journal prefers to punctuate the phrase (as an adjective and as an adverb). If the journal is consistent, follow the preferences of the journal. If the journal is inconsistent, then you have room to choose, as long as your paper is internally consistent.

  • Hello, 388. Perfectly sound advice, but about the hundredth repeat. – Edwin Ashworth Jun 14 '20 at 14:33

An interesting test could be to replace the Latin phrase with its English equivalent: "in position." Using the common test of decomposing the phrase from right to left on the phrase "in situ visualization," try "in position visualization." The phrase "position visualization" may not make sense to the reader, causing the to try to interpret "in position visualization" with "in position" combined, as if it did have a hyphen. Hyphenating the phrase ("in-position visualization") seems preferable here. I agree with @phenry that using a hyphen will only help the reader avoid a double-take on the phrase, especially if they are unfamiliar with the Latin phrase.

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