Hyphen in Anti-malware but not Antivirus

Question

Why is there a hyphen in Anti-malware but not a hyphen in antivirus. I have found nothing, no matter how far I have searched hence my presence on this site.

Answer 1

Hyphenation of affixes (in English, usually prefixes and suffixes) is arbitrary, in the sense that it comes down to style guides and conventions of usage, rather than a single consistent set of rules. For example, here is the advice given in APA and Chicago:

APA:

A hyphen should be used with a prefix under the following conditions:

• The word could be misread without a hyphen (e.g., re-pair, meaning to pair again, vs. repair, meaning to fix).
• The double vowels aa, ii, oo, or uu would occur without a hyphen (e.g., anti-intellectual is correct, not antiintellectual).
• The word that follows the hyphen is capitalized (e.g., un-American).
• The word that follows the hyphen begins with a numeral (e.g., mid-2016).
• The word is shown as permanently hyphenated in Merriam-Webster’s dictionary (e.g., pro-choice).
• A prefix is being added to a compound word that is already hyphenated (e.g., adding post- to graduate-level students creates post-graduate-level students, but if the phrase is just graduate students [no hyphen] then adding post- as a prefix gives you the regular hyphenless postgraduate students).

Chicago:

Compounds formed with prefixes are normally closed, whether they are nouns, verbs, adjectives, or adverbs. A hyphen should appear, however, (1) before a capitalized word or a numeral, such a[s] sub-Saharan, pre-1950; (2) before a compound term, such as non-self-sustaining, pre-Vietnam War (before an open compound, an en-dash is used; see 6.80); (3) to separate two i's, two-a's, and other combinations of letters or syllables that might cause misreading, such as anti-intellectual, extra-alkaline, pro-life; (4) to separate the repeated terms in a double-prefix, such as sub-subentry; (5) when a prefix or combining form stands alone, such as over- and underused, macro- and microeconomics. The spellings shown below conform largely to Merriam-Webster's Collegiate Dictionary."

In this case, both style guides illustrate two possible explanations for anti-malware but antivirus in their formats:

1. To limit misreading. Because mal is already an abbreviation of malicious, -ware is already a suffix, and malware is a relatively new word, antimalware has a greater probability of being misread or mispronounced. (Ex. antimal-ware.) The hyphen clarifies the root from the prefix/suffix. Virus, being a well-known word with no other affixes, is less likely to be misread without a hyphen.

2. To conform to standard use in dictionaries. Anti-malware usually does not appear in dictionaries, and this includes Merriam-Webster, the dictionary of choice for APA and Chicago. Antivirus does, in unhyphenated form.

In addition, affixes tend to join their words and become unhyphenated over time if the words are often used. Antivirus has been a word since 1892, according to Merriam-Webster, is used in two distinct fields (medicine and computing), and many users are familiar with the word. Malware has been a word since about 1990, which means anti-malware is still newer, and perhaps hasn't become familiar enough to drop the hyphen.

So that's three possible explanations for hyphenation. Two, preventing misreading and aligning with dictionary documentation, are general guidelines a style guide might suggest to create consistency. The third, the progression of time making formerly-hyphenated words familiar enough to omit the hyphen, is an arbitrary phenomenon that admits exceptions.