According to my armchair research on common abbreviations of nota bene, it appears that NB is the most common now, with N.B. being more common in centuries past after taking over the "original" nb in the early 1700s. While n.b. is the least common by far. This is very different from i.e. and e.g..

Some abbreviations like etc. and et al. aren't taken down to single letters, but almost every Latin->English abbreviation I know of is lower case, and includes at least one period. Etymologies I look up just talk about the Latin origins, but don't talk about how the particular glyphs were chosen.

Why is NB typically capitalized, and why the common lack of periods?

  • 14
    The often-swapped i.e. and e.g. sit mid-sentence, whereas NB always begins sentences to announce a key pointer. So that justifies at least the initial initial. And it's a bit like a traffic sign or billboard with capitalized words. Commented Dec 31, 2022 at 23:57
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    Something simiilar happens with other abbreviations: QED, PS, QEI, USA, ...
    – Sofronias
    Commented Jan 1, 2023 at 11:22
  • 3
    @Ananias Indeed — it looks like ‘i.e.’ and ‘e.g.’ are the odd ones out that need explaining. (I expect it's just historical accident, but I'd be interested to see any actual evidence.)
    – gidds
    Commented Jan 1, 2023 at 20:26
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    @Ananias There are many, many Latin abbreviations that are normally majusculated, like these and these. Copious examples include A.D., C.V., D.G., J.D., M.D., M.O., N.P.O., O.D., O.S., Ph.D., P.R.N., R.I.P., S.D.G., Th.D., et hoc genus omne. :)
    – tchrist
    Commented Jan 1, 2023 at 22:12
  • 1
    @tchrist is R.I.P. Latin? Most of those examples are titles, right? Those seem different than i.e., e.g., cf, ibid, et al., and so on, which are just shorthand words rather than titles. Commented Jan 2, 2023 at 5:27

7 Answers 7


Here is what The Chicago Manual of Style has to say:

NB, n.b.     nota bene, take careful note (capitals are illogical but often used for emphasis)

Source: The Chicago Manual of Style (login required)

It's not a terribly satisfying answer, but such is often the case when style is the operative word.

  • 3
    Doesn't the style follow the English words we would naturally choose instead? We write i.e. and e.g. after a comma, so treat them the way we would treat "that is" following a comma; and we usually write NB as the beginning of a sentence.
    – Chaim
    Commented Jan 1, 2023 at 20:44
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    @Chaim — Then why not Nb or N.b. at the beginning of a sentence? Would you start a sentence with For Example with a capital E? This is style, not logic. Commented Jan 2, 2023 at 2:37
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    Well I would say that the truth lies somewhere in the middle. I agree that if we were treating NB as two English words, Nb would make more sense than NB. But Nb looks pretty awful, and the analogy to ordinary English seems relevant although imperfect. Can you think of many analogies to Nb, with just the first letter capitalized?
    – Chaim
    Commented Jan 2, 2023 at 3:10
  • 1
    Niobium: do not confuse chemical symbols with other unrelated abbreviations. Commented Jan 3, 2023 at 8:12
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    @SO_fix_the_vote_sorting_bug People do often write NOTE in all capitals for emphasis.
    – xngtng
    Commented Jan 3, 2023 at 10:19

NB or N.B. usually introduces a sentence, whereas i.e. and e.g. usually come in the middle of one.


It's likely that that all caps version is favored because of the intent. "Nota bene" apparently means, "pay extra attention!" and, since n.b! looks weird and jarring, the all caps was chosen for emphasis.

  • 16
    "looks weird and jarring"? That would be because we're not used to it, so it's a circular argument. Commented Jan 2, 2023 at 13:37

I checked some of the style guides in my library to see what they had to say about the preferred form of n.b/nb/N.B./NB, and this is what they had to say (sources are arranged in chronological order, oldest to newest).

From Bergen Evans & Cornelia Evans, A Dictionary of Contemporary American Usage (1957):

n.b. This is an abbreviation of the Latin words nota bene and means "note well."

From Wilson Follett, Modern American Usage: A Guide (1966):

abbreviations. 1. The modern tendency in scholarship as well as popular works is to replace the Latin abbreviations by English ones; for example, ... note for N.B.

From Words into Type, third edition (1974):

The following Latin abbreviations, including some seen only in older works, are not often appropriate to text except parenthetically but are useful in footnote material:

N.B. (nota bene), mark well

From Warriner's English Grammar and Composition, Fifth Course (1977):

N.B. note well (from the Latin nota bene); always italicized or underlined.

From [Merriam-]Webster's Standard American Style Manual (1985):

Latin Words and Phrases

25. Words and phrases derived from Latin are commonly abbreviated in contexts where readers can reasonably be expected to recognize them. They are punctuated, not capitalized, and usually not italicized.

[Examples:] etc. | i.e. | e.g. | viz. | eta al. | pro tem.

Although this style guide omits any direct mention of nota bene, it seems fair to infer from the prescriptive and categorical approach to the topic of Latin abbreviations that it would endorse the form n.b.

From Stuart Miller, Concise Dictionary of Acronyms and Initialisms (1988):

n.b. Nota bene (Latin: "note well")

From Robert Hendrickson, The Facts on File Dictionary of Word and Phrase Origins, second edition (1997):

N.B. This is the abbreviation used for the Latin nota bene, "note well, take notice," often used in literary and scholarly works. Voltaire told of how a commentator on Lucretius by the name of Creech noted on his manuscript: "N.B. Must hang myself when I have finished." According to Voltaire, "He kept his word, that he might have the pleasure [of committing suicide] like Lucretius. Had he written upon Ovid, he would have lived longer."

From Joseph Gibaldi, MLA Style Manual and Guide to Scholarly Publishing, second edition (1998):

NB take notice (from Lat. nota bene; always capitalized)

From The Oxford Dictionary for Writers and Editors (2000):

NB New Brunswick, North Britain, (Lat.) nota bene (mark well)

According to this Oxford style guide, "n.b." stands for "no ball" in cricket.

From Martin Manser, The Facts on File Dictionary of Foreign Words and Phrases (2002):

nota bene LATIN {mark well} verb phrase note well, observe particularly. ~abbreviated forms n.b., N.B.

From Andrea Lunsford, The St. Martin's Handbook, fifth edition (2003):

Latin abbreviations

In general, avoid these abbreviations except when citing sources:


N.B. note well (nota bene)

From Bryan Garner, Garner's Modern American Usage, second edition (2003):

N.B. is the abbreviation for the Latin nota bene (= note well; take notice).

And from The Chicago Manual of Style, sixteenth edition (2010):

NB, n.b. nota bene, take careful note (capitals are illogical but often used for emphasis)

The raw vote totals from these reference guides (counting both options offered by CMoS sixteenth edition and by Manser) is as follows:

  • nb 0 votes
  • n.b. 4 votes (plus one prescriptive guideline that would seem to require it), ranging from 1957 to 2010
  • N.B. 7 votes (including one specifying that it should always be italicized or underlined), ranging from 1966 to 2003
  • NB 3 votes, ranging from 1998 to 2010

Opposition to italicizing the Latin abbreviations thus seems to have begun at an early date, with little counterargument. Both the n.b. and N.B. forms of that abbreviation have had their adherents among style guides across the years, without pressing the rival punctuated form to the periphery. And NB has emerged relatively late—an unsurprising development, given the more general trend toward punctuationless abbreviations in recent years. Perhaps the more forward-looking question would be, By what date are i.e. and e.g. likely to lose their periods in standard usage?


The literal answer to your question is, simply:

  • Literal answer to your question: there is no logical reason whatsoever.

In the question, you have excellently shown that the most popular variation, changes, over time and place.

Everyone has explained, at length, very properly, reasonable "logical" quasi-arguments for each.

It's just like asking "What is the logical reason laser become a word but VIP remains an acronym in English (but in Germany people pronounce it as a word, and we may do so in the future in English) ?". The answer is "there is no logical reason."

Indeed, it's just like asking "What is the logical reason spelling S of word W?"

If (you happen to want to), you would use the most common styling seen in your milieu. This is why newspapers, universities, professional groups, etc, (sometimes) state "We use style _ _ _".

  • The default definition of 'acronym' classes 'laser', 'NASA' and 'ISA' as acronyms (of which the first has certainly entered the lexicon) but 'VIP', 'BBC' as initialisms ('spelled out'). And CMOS's '(capitals are illogical but often used for emphasis)' is a 'logical reason', as you concede. I don't see how 'there is no logical reason whatsoever' sits alongside this; you seem to be saying CMOS is incorrect here. Commented Jan 3, 2023 at 14:51
  • Hi EA, any style manual is not "correct or incorrect". It is literally a style manual. (Much as corporations will have a "style manual" which states, the logo must be XYZ color, the typeface you use must be XYZ color and so on.) Those things are not "correct or incorrect" they are a stated style. Sure, style manuals may include as an addendum the reason for their thinking. My post is very clear (and I'm so modest about that :) ) and I'm really just repeating myself.
    – Fattie
    Commented Jan 3, 2023 at 18:00
  • Regarding the CMOS. and "nb". (1) The CMOS is poorly written. (2) The CMOS is very poor conceptually (for example, for color/colour the suggestion is: "go with your local dictionary!!) (3) It's a very "soft" style manual, it should be titled "The Chicago Interesting Thoughts On Spelling And Stuff"! :) (4) Regarding "nb", my reading of their entry is "use nb; NB is a bit illogical. As usual since this is the CMOS, you now have no idea what to do!" (5) If you have a different reading of their entry, that's fine. I think their entry is weak, but moreover, style manuals are just style manuals.
    – Fattie
    Commented Jan 3, 2023 at 18:04

I can't say why both are used, but I can say which is more common:

According to Google Ngram, NB has been more frequently used that N.B. since c. 1960.

(And, considering casing, "n.b." is hardly used at all.)

  • I'm not sure that Google Ngram is to be trusted here. I see results like "NB-IoT" and other false positives. On the first page of results, I don't actually see any true positives. Maybe using a different corpus tool such as COCA would help, maybe not—at least with that you could check the results to account for false positives.
    – Laurel
    Commented Dec 8, 2023 at 15:47

Maybe there's some historical reason for it. But mostly, I think, it's just convention. There are lots of things in language that are the way they are just because many people over a long period of time have done them that way. You might as well ask, "Why is the word for a domesticated canine 'dog' and not 'ariwinkle'?" It just is.

Okay, I say this whimsically. If there was some good logical reason or at least pattern why some abbreviations are written in caps and others in small letters it would be helpful to people learning that language. But I think there just ... isn't.

  • 1
    But this has already been said. Commented Jan 8 at 18:46

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