ad hoc

1. 1
   for one jobadjective

   Formed, arranged, or done for a particular purpose rather than for general use.

   The board appointed an ad hoc committee to investigate the accounting errors and report back by June.

   Instead of buying general software, the lab wrote an ad hoc script to clean the data from that one survey.

   Similarspecial, dedicated

   Oppositepermanent, standing, general

   Note

   The sense that keeps the Latin meaning: New Latin ad hoc, "to this, for this." Whatever it describes exists for the task at hand. A committee can be planned with great care and still be ad hoc, because the word judges purpose, not preparation. That is what separates it from the "improvised" meaning. It compares with more and most: a more ad hoc arrangement.

2. 2
   adjective

   Created or arranged on the spur of the moment, without advance planning.

   Before any agency arrived, ad hoc crews of neighbors were already filling sandbags along the river.

   The encore was entirely ad hoc, a song the band had never rehearsed together.

   Similarimprovised, impromptu, spontaneous, unplanned, makeshift

   Oppositeplanned, rehearsed, organized

3. 3
   adverb

   For a particular purpose, rather than for general use.

   The tribunal was convened ad hoc to hear disputes arising from the border treaty.

   Rather than keep translators on staff, the agency hires them ad hoc for each case that needs one.

   Similarspecially

4. 4
   adverb

   On the spur of the moment, without a plan made in advance.

   No agenda had been sent out, so the topics were chosen ad hoc as people arrived.

   When two starters fell ill during warm-ups, the coach reshuffled the lineup ad hoc.

   Similarspontaneously

5. 5
   saving a theoryadjective

   Describing a hypothesis put forward solely to keep a theory from being falsified, without making any new predictions.

   Faced with the stray orbit, defenders of the model proposed an ad hoc hypothesis: an undetectable mass whose only job was to make the numbers fit.

   Reviewers dismissed the added hypothesis as ad hoc, since it explained away the failed result but predicted nothing testable.

   Note

   Among scientists the word is a charge, not a neutral description, and it attaches to hypotheses: an ad hoc hypothesis, or one dismissed as ad hoc. A long tradition condoned such moves. J. Agassi's Science in Flux, siding with Popper and Grünbaum, takes the harder line: once an ad hoc hypothesis is introduced, "we are unhappy about it and try to eliminate it."

6. 6
   computer networkadjective

   Describing a network or connection that works without existing infrastructure such as routers or access points.

   After the earthquake knocked out the cell towers, the rescue teams' handheld radios formed an ad hoc network, linking directly to one another.

   In ad hoc mode, each sensor relays messages for its neighbors, so the system needs no access point.

   Note

   Networking took the phrase for systems with no fixed backbone. An ad hoc network is temporary by nature. Wireless mobile nodes form it dynamically among themselves, with no central administration, and it lasts only as long as they need it, much as the "for this purpose" sense would suggest.

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