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As the title says, I'm wondering if "non-linear" is an acceptable spelling of the word "nonlinear."

A bit of research on this site turns up Is the use of a hyphen between "non" and an adjective strictly necessary?, in which Monica Cellio commented that some of these "non"-prefixed words have entered the language in unhyphenated form. This is the way I'm used to seeing "nonlinear." But other people I work with spell it with the hyphen, "non-linear." Is that valid, or should I point it out as a correction? (This is in a scientific paper going to publication; I wouldn't care in a less formal context)

More generally, what reference(s) would I look at to answer questions like this in the future, about whether a particular compound can/should be spelled with or without a hyphen?

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While it's strictly correct to omit the hyphen, and technically it's either incorrect or out of favor to use the hyphen, in my experience only the tiniest percentage of people know this, even very formal writers, especially if they are not English geeks like us. ;) I'll bet you find non-linear in plenty of reputable publications. (Note: By all means, I strongly recommend omission of the hyphen!) – John Y Jul 1 '11 at 19:33
up vote 9 down vote accepted

According to Hyphenated Words: A Guide

You would not use a hyphen with the prefix non unless it is before a proper noun.

Do not hyphenate words prefixed by non, un, in, dis, co, anti, hyper, pre, re, post, out, bi, counter, de, semi, mis, mega, micro, inter, over, and under (among others).

Examples: nonaffiliated, nonemergency, uninfected, inpatient, disorder, disbar, coworker, copayment, antismoking, antimanagement, hyperactive, hyperrealism, preoperative, prejudge, reoccur, readjust, resubmit, postoperative, posttraumatic, outpatient, outmoded, bimonthly, biannual, counterrevolutionary, counterculture, decompress, semifinal, semiannual, misinformed, misprint, megabyte, microcircuit, interconnected, interoffice, overempha­size, override, underrepresent, underestimated.

EXCEPTIONS: When the second element is capitalized, as in Un-American and non-English, a hyphen is used. Also, occasional exceptions exist where the prefix and the second element have not (yet) "grown together," such as de-emphasize, pre-owned, co-op (to distinguish from coop) and anti-inflammatory (and all words with anti- prefix and second element beginning with i)

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I think that, on top of the one exception for capitalized proper nouns, if the use of "non-" preceding a term is previously unseen then the hyphenated spelling may be acceptable. However, this doesn't excuse "non-linear" as the term is common in mathematics (which I hope we all took to a point where this term is known); the spelling is "nonlinear" and the hyphen should not be used here. – KeithS Jul 1 '11 at 20:07
+1 For the reference to the Guide – Thursagen Jul 2 '11 at 5:20
That guide's proposed rule looks suspicious to me. Particularly, "nonemergency", "antismoking", "antimanagement", and "interoffice" look strange without a hyphen. Also, "posttraumatic" (though the DSM spells it without a hyphen) – Mechanical snail Oct 11 '11 at 1:56

The first three dictionaries I looked in all give nonlinear as the entry with no alternate non-linear. Here's NOAD:

nonlinear |nänˈlinēər| adjective
1 not denoting, involving, or arranged in a straight line.
• Mathematics designating or involving an equation whose terms are not of the first degree.
• Physics involving a lack of linearity between two related qualities such as input and output.
• Mathematics involving measurement in more than one dimension.
• not linear, sequential, or straightforward; random : Joyce's stream-of-consciousness, nonlinear narrative.
2 of or denoting digital editing whereby a sequence of edits is stored on computer as opposed to videotape, thus facilitating further editing.

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+1; in addition to nonlinear, searching the dictionary reveals plenty of words that start with non but do not include a hyphen. Examples: nonblack, nonbiological, noncombatant. – MrHen Jul 1 '11 at 19:08

The Oxford Dictionary (which I personally consider the reference for the English language) lists "non-linear" as the correct British spelling and no alternative is given. But if you switch to the US English dictionary, the only entry is "nonlinear".

Source: http://www.oxforddictionaries.com/

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+1 for the Oxford English Dictionary. This is my primary reference too. – onewhaleid May 1 '15 at 7:47

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