bug
     n 1: general term for any insect or similar creeping or crawling
          invertebrate
     2: a fault or defect in a system or machine [syn: {glitch}]
     3: a small hidden microphone; for listening secretly
     4: insects with sucking mouthparts and forewings thickened and
        leathery at the base; usually show incomplete
        metamorphosis [syn: {hemipterous insect}, {hemipteran}, {hemipteron}]
     5: a minute life form (especially a disease-causing bacterium);
        the term is not in technical use [syn: {microbe}, {germ}]
     v 1: annoy persistently; "The children teased the boy because of
          his stammer" [syn: {tease}, {badger}, {pester}, {beleaguer}]
     2: tap a telephone or telegraph wire to get information; "The
        FBI was tapping the phone line of the suspected spy"; "Is
        this hotel room bugged?" [syn: {wiretap}, {tap}, {intercept}]
     [also: {bugging}, {bugged}]
Source: WordNet® 2.0

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!

   Or perhaps not a joke. Historians of the field inform us that the term
   "bug" was regularly used in the early days of telegraphy to refer to a
   variety of semi-automatic telegraphy keyers that would send a string of
   dots if you held them down. In fact, the Vibroplex keyers (which were
   among the most common of this type) even had a graphic of a beetle on
   them (and still do)! While the ability to send repeated dots
   automatically was very useful for professional morse code operators,
   these were also significantly trickier to use than the older manual
   keyers, and it could take some practice to ensure one didn't introduce
   extraneous dots into the code by holding the key down a fraction too
   long. In the hands of an inexperienced operator, a Vibroplex "bug" on
   the line could mean that a lot of garbled Morse would soon be coming
   your way.

   Further, the term "bug" has long been used among radio technicians to
   describe a device that converts electromagnetic field variations into
   acoustic signals. It is used to trace radio interference and look for
   dangerous radio emissions. Radio community usage derives from the
   roach-like shape of the first versions used by 19th century physicists.
   The first versions consisted of a coil of wire (roach body), with the
   two wire ends sticking out and bent back to nearly touch forming a spark
   gap (roach antennae). The bug is to the radio technician what the
   stethoscope is to the stereotypical medical doctor. This sense is almost
   certainly ancestral to modern use of "bug" for a covert monitoring
   device, but may also have contributed to the use of "bug" for the
   effects of radio interference itself.

   Actually, use of `bug' in the general sense of a disruptive event goes
   back to Shakespeare! (Henry VI, part III - Act V, Scene II: King Edward:
   "So, lie thou there. Die thou; and die our fear; For Warwick was a bug
   that fear'd us all.") 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 was not actually
   exhibited for years afterwards. Thus, the process of investigating the
   original-computer-bug bug fixed it in an entirely unexpected way, by
   making the myth true! --ESR]


Source: The Jargon File