# What is the plural of proof of concept? Is it proofs of concept, proof of concepts or proofs of concepts? [closed]

Can someone please clarify what is the plural form of proof of concept? Is it proofs of concept, proof of concepts or proofs of concepts?

• I would simply say `POCs`.. Most people use the abbreviated form in conversations.. to say the whole thing is so tiring.. – Ronnie Jun 22 '12 at 15:15
• While writing formally `proof-of-concept's` could be used I guess.. – Ronnie Jun 22 '12 at 15:21
• It might depend on you have many different proofs of one concept, or many different proofs of many different concepts. – FrustratedWithFormsDesigner Jun 22 '12 at 15:22
• @userSeven7s no. That is so wrong I don't know where to start. – RegDwigнt Jun 22 '12 at 15:24
• I am closing this as general reference, since Wiktionary has the answer. See also: Words that are pluralized in the middle. – RegDwigнt Jun 22 '12 at 15:27

It's proofs of concept.

As the moderator's closure comment indicates, the Wiktionary:Talk page is a good reference; e.g. compare to "mothers-in-law" or "attorneys-at-law."

• What if I have multiple proofs of multiple concepts? as @FrustratedWithForms. said.. – Ronnie Jun 22 '12 at 15:29
• Then you would have multiple proofs of concept, not "proofs of concepts" – ish Jun 22 '12 at 15:33
• @Ronnie your question seems inadvertently redundant. Proof of concept is one proof for one general concept. Proofs of concept are multiple proofs for one general concept. "Proofs of concept" is a grouping; so multiple groups would just be as ish said, multiple proofs of concept. While each concept can have multiple proofs, it is unlikely that one proof will apply to discrete concepts. As it is already a grouping, saying multiple doesn't really change its plurality. I get what you're trying to say, but you're sort of inventing a novel problem that doesn't really need to be further solved. – kayleeFrye_onDeck Jun 5 '18 at 19:02

If you consider proof of concept a compound phrase, it would be proofs of concept. In The Associated Press Stylebook, it says for compound words that involve separate words or words linked by a hyphen, make the most significant word plural:

• Significant word first: adjutants general, aides-de-camp, attorneys general, courts-martial, daughters-in-law, passers-by, postmasters general, presidents-elect, secretaries general, sergeants major
• Significant word in the middle: assistant attorneys general, deputy chiefs of staff
• Significant word last: assistant attorneys, assistant corporation counsels, deputy sheriffs, lieutenant colonels, major generals
• I've always wondered whether cul-de-sac happens to follow this rule. – cornbread ninja 麵包忍者 Jun 22 '12 at 16:23
• Per my American Heritage Dictionary, 4th ed., it can be either culs-de-sac or cul-de-sacs. I would guess in U.S. suburbia, that cul-de-sacs is more commonly used. – JLG Jun 22 '12 at 16:32
• Stating the rule in terms of "most significant word" seems unnecessarily ambiguous to me. I learned it as "make the noun plural, not any adjective or other modifiers". So, for example, a "court martial" is a court that is martial (i.e. related to the military), not a martial that is court. So to make it plural, we say "courts martial", because there are two courts, not two "martials". Granted it can be confusing because in some cases a word can be both a noun and an adjective, but we have to look at how it's used in this particular phrase. ... – Jay Jun 22 '12 at 17:29
• ... Like "attorney general". Yes, "general" can be a noun, as in the military rank. But here it's being used as an adjective. The "attorney" has "general" authority. – Jay Jun 22 '12 at 17:30