Sign up ×
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It's 100% free, no registration required.

Should the word be written as X-ray or x-ray?

share|improve this question
Let's throw the hyphen into the debate. As a legal transcriptionist, I rely on Merriam Webster's Legal Speller. It shows x-ray as a verb, and X ray as a noun. – user10358 Jun 27 '11 at 4:42

4 Answers 4

up vote 12 down vote accepted

Wikipedia capitalizes the X. Wiktionary says that x-ray is the alternative spelling of X-ray, not the other way round. Merriam-Webster capitalizes the noun but not the verb, noting that the verb is "often capitalized", too.

Looking through the first 250 cites in the Corpus of Contemporary American English, the capitalized version is preferred by a factor of 2:1; looking through the first 250 cites in the British National Corpus, it wins by a factor of 11:1.

share|improve this answer
+1 for a great answer. Much more comprehensive than mine. – Tragicomic Jan 25 '11 at 9:58
I am assuming the British know their language then and will switch to X-ray. – Johan Jan 25 '11 at 10:07
Point of Fact: It appears that William Röntgen capitalized the X and, since he named the dang things, I say we go with his spelling. I would also cite Google Ngram which shows both a greater prevalence and earlier appearance of X-ray over x-ray. – Engineer Toast Apr 1 at 18:49

When used as a noun or a modifier, the "X" in X-ray is capitalized.

  • The doctor looked at the patient's X-ray.
  • Do you think all superheroes have X-ray vision?

When it is used as a verb, the "X" is usually capitalized.

  • Your chest needs to be X-rayed.

However, the entry on Merriam Webster Online for X-ray as a verb lists it with a small "X". It does say, though, that the verb is often capitalized.

share|improve this answer
Yeah, I've definitely seen uses of both X-ray and x-ray. But the capitalized version is more common? – Johan Jan 25 '11 at 9:37
OED online has only the capitalized spelling. The only reference I could find to the lowercase x-ray was in Merriam Webster Online, and only when it is a verb. It is capitalized whenever it is used as a noun. – Tragicomic Jan 25 '11 at 9:46
The NOAD reports that you can write X-ray, x-ray, or X ray, but the entry in the dictionary is for X-ray. – kiamlaluno Jan 26 '11 at 12:54

I work on veterinary journals and our go-to dictionaries are Dorland's Illustrated Medical Dictionary (30th Ed.) and Saunders Comprehensive Veterinary Dictionary (2nd Ed.) Neither of these capitalizes x-ray (as a verb or a noun), and both dictionaries show that a hyphen is used.

I am not sure where the OP is using the term, but it seems that in medical literature the word radiograph is preferred over x-ray. Also, our authors rarely, if ever, use x-ray as a verb.

share|improve this answer
So what do they use as a verb? "Radiographing"? – Johan Apr 1 '12 at 14:24
They use radiograph as the verb. "We radiographed the dog's leg." Or they say they "perform radiography." – JLG Apr 1 '12 at 14:51

According to the Chicago Manual of Style, 16th edition, x-ray is not capitalized. Not when it's a noun, a verb, or an adjective. This is the standard for fiction writing.

I am both a speech-language pathologist and a fiction writer.

share|improve this answer

protected by Will Hunting Mar 23 '12 at 0:46

Thank you for your interest in this question. Because it has attracted low-quality answers, posting an answer now requires 10 reputation on this site.

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.