The Collaborative International Dictionary of English v.0.48:

Fud \Fud\, n. [Of uncertain origin.]
   1. The tail of a hare, coney, etc. [Prov. Eng. & Scot.]
      --Burns.
      [1913 Webster]

   2. Woolen waste, for mixing with mungo and shoddy.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "fud":
   Methuselah, antediluvian, antique, back number, conservative, dad,
   dodo, elder, fogy, fossil, fuddy-duddy, granny, has-been, longhair,
   matriarch, mid-Victorian, mossback, old believer, old crock,
   old dodo, old fogy, old liner, old man, old poop, old woman,
   old-timer, patriarch, pop, pops, reactionary, regular old fogy,
   relic, square, starets, traditionalist



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

FUD
       Fear, Uncertainty & Doubt (slang, IBM)


The Jargon File (version 4.4.7, 29 Dec 2003):

FUD
 /fuhd/, n.

    Defined by Gene Amdahl after he left IBM to found his own company: ?FUD is
    the fear, uncertainty, and doubt that IBM sales people instill in the minds
    of potential customers who might be considering [Amdahl] products.? The
    idea, of course, was to persuade them to go with safe IBM gear rather than
    with competitors' equipment. This implicit coercion was traditionally
    accomplished by promising that Good Things would happen to people who stuck
    with IBM, but Dark Shadows loomed over the future of competitors' equipment
    or software. See IBM. After 1990 the term FUD was associated increasingly
    frequently with Microsoft, and has become generalized to refer to any
    kind of disinformation used as a competitive weapon.

    [In 2003, SCO sued IBM in an action which, among other things, alleged
    SCO's proprietary control of Linux. The SCO suit rapidly became infamous
    for the number and magnitude of falsehoods alleged in SCO's filings. In
    October 2003, SCO's lawyers filed a memorandum in which they actually had
    the temerity to link to the web version of this entry in furtherance of
    their claims. Whilst we appreciate the compliment of being treated as an
    authority, we can return it only by observing that SCO has become a nest of
    liars and thieves compared to which IBM at its historic worst looked
    positively angelic. Any judge or law clerk reading this should surf through
    to my collected resources on this topic for the appalling details.?ESR]


The Free On-line Dictionary of Computing (30 December 2018):

FUD

    /fuhd/ An acronym invented by Gene Amdahl
   after he left IBM to found his own company: "FUD is the
   fear, uncertainty, and doubt that IBM sales people instill
   in the minds of potential customers who might be considering
   [Amdahl] products."  The idea, of course, was to persuade them
   to go with safe IBM gear rather than with competitors'
   equipment.  This implicit coercion was traditionally
   accomplished by promising that Good Things would happen to
   people who stuck with IBM, but Dark Shadows loomed over the
   future of competitors' equipment or software.

   [Jargon File]

   (1995-05-23)