bug

bug n.  An unwanted and unintended property of a program or
   piece of hardware, esp. one that causes it to malfunction.
   Antonym of {feature}.  Examples "There's a bug in the editor
   it writes things out backwards."  "The system crashed because of
   a hardware bug."  "Fred is a winner, but he has a few bugs"
   (i.e., Fred is a good guy, but he has a few personality problems).

   Historical note: Admiral Grace Hopper (an early computing pioneer
   better known for inventing {COBOL}) liked to tell a story in
   which a technician solved a {glitch} in the Harvard Mark II
   machine by pulling an actual insect out from between the contacts
   of one of its relays, and she subsequently promulgated {bug} in
   its hackish sense as a joke about the incident (though, as she was
   careful to admit, she was not there when it happened).  For many
   years the logbook associated with the incident and the actual bug
   in question (a moth) sat in a display case at the Naval Surface
   Warfare Center (NSWC).  The entire story, with a picture of the
   logbook and the moth taped into it, is recorded in the "Annals
   of the History of Computing", Vol. 3, No. 3 (July 1981),
   pp. 285--286.

   The text of the log entry (from September 9, 1947), reads "1545
   Relay #70 Panel F (moth) in relay.  First actual case of bug being
   found".  This wording establishes that the term was already
   in use at the time in its current specific sense -- and Hopper
   herself reports that the term `bug' was regularly applied to
   problems in radar electronics during WWII.

   Indeed, the use of `bug' to mean an industrial defect was already
   established in Thomas Edison's time, and a more specific and rather
   modern use can be found in an electrical handbook from 1896
   ("Hawkin's New Catechism of Electricity", Theo. Audel & Co.)
   which says: "The term `bug' is used to a limited extent to
   designate any fault or trouble in the connections or working of
   electric apparatus."  It further notes that the term is "said to
   have originated in quadruplex telegraphy and have been transferred
   to all electric apparatus."

   The latter observation may explain a common folk etymology of the
   term; that it came from telephone company usage, in which "bugs in
   a telephone cable" were blamed for noisy lines.  Though this
   derivation seems to be mistaken, it may well be a distorted memory
   of a joke first current among *telegraph* operators more than
   a century ago!

   Actually, use of `bug' in the general sense of a disruptive event
   goes back to Shakespeare!  In the first edition of Samuel Johnson's
   dictionary one meaning of `bug' is "A frightful object; a
   walking spectre"; this is traced to `bugbear', a Welsh term for
   a variety of mythological monster which (to complete the circle)
   has recently been reintroduced into the popular lexicon through
   fantasy role-playing games.

   In any case, in jargon the word almost never refers to insects.
   Here is a plausible conversation that never actually happened:

   "There is a bug in this ant farm!"

   "What do you mean?  I don't see any ants in it."

   "That's the bug."

   A careful discussion of the etymological issues can be found in a
   paper by Fred R. Shapiro, 1987, "Entomology of the Computer Bug:
   History and Folklore", American Speech 62(4):376-378.

   [There has been a widespread myth that the original bug was moved
   to the Smithsonian, and an earlier version of this entry so
   asserted.  A correspondent who thought to check discovered that the
   bug was not there.  While investigating this in late 1990, your
   editor discovered that the NSWC still had the bug, but had
   unsuccessfully tried to get the Smithsonian to accept it -- and
   that the present curator of their History of American Technology
   Museum didn't know this and agreed that it would make a worthwhile
   exhibit.  It was moved to the Smithsonian in mid-1991, but due to
   space and money constraints has not yet been exhibited.  Thus, the
   process of investigating the original-computer-bug bug fixed it in
   an entirely unexpected way, by making the myth true!  -- ESR]