We can describe something as pre-emptive, no issue there.

If something isn't such, how can we write that? Word gives me red squiggles on 'Non-preemptive', but this looks silly with a double hyphenation.

Which leads me to wonder why 'pre-emptive' is hyphenated anyway? 'Emptive' isn't a word, and other 'pre' prefixes aren't hyphenated (e.g. prefix, predecessor).

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    If it isn't preemptive, it's reactive
    – Andy
    Jun 10, 2014 at 17:08
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    @OllieFord For the computer science term I'd use nonpreemptive multitasking. Jun 10, 2014 at 17:15
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    emptor is a word for buyer, emption is a word for buying. Neither in common use these days except for caveat emptor. Pre-emptor (or preemptor) is someone who has struck a deal to buy something before it is offered to the general public. I imagine (which why this isn't an answer) is that empt became the part of the word preempt to mean 'prior action' not just buying stuff.
    – Frank
    Jun 10, 2014 at 17:16
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    Ollie Ford, the spelling seems to be a US/UK difference. See the Hyphens section at the bottom of the page, at this link lukemastin.com/testing/spelling/cgi-bin/…
    – Tristan r
    Jun 10, 2014 at 17:36
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    @Andy - Ironically, in computing, pre-emptive operating systems are more reactive than non-preemptive ones! :) Jun 15, 2014 at 10:10

2 Answers 2


There are two possibile ways to describe something that is not pre-emptive.

1) Non-preemptive.

This is used in computing. In this context, the choice of hypenation appears arbitrary. A simple google seach for nonpreemptive operating system shows that one hyphen is the most common choice. "Non-preemptive operating systems are not a good choice in a situation where reaction time is important".

2) Reactive or reactionary.

This is used in a military context. "They decided not to make a pre-emptive strike. As a result, their strikes, when they finally responded to provocation, were reactionary, and all too late..."

  • +1, all good stuff. I would simply add that the preventive/reactive dichotomy exists in other fields than the military example given, such as medicine and maintenance.
    – naughtilus
    Jul 9, 2014 at 11:46

First, I wouldn't hypenate preemptive and Webster's and other lexicographers googled tended to agree (but see Cambridge and Oxford).

And, I thought pre-emptor was the best answer.

But your reference to "emptive" or "empt" led me to a thesis. Empt is listed in Webster's as Definition of empt ++ -ed/-ing/-s ++ now dialectal : empty.

Agreeing with another response, the opposite of preempt is react. To react is to respond to a causal act. To prempt is to respond without, or in advance of, a causal act -- a response to empty or nothing.

BTW, I got here after having used "post-emptive" facetiously to describe conduct.

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