The Collaborative International Dictionary of English v.0.48:

Disclaimer \Dis*claim"er\, n.
   1. One who disclaims, disowns, or renounces.
      [1913 Webster]

   2. (Law) A denial, disavowal, or renunciation, as of a title,
      claim, interest, estate, or trust; relinquishment or
      waiver of an interest or estate. --Burrill.
      [1913 Webster]

   3. A public disavowal, as of pretensions, claims, opinions,
      and the like. --Burke.
      [1913 Webster]

WordNet (r) 3.0 (2006):

disclaimer
    n 1: (law) a voluntary repudiation of a person's legal claim to
         something
    2: denial of any connection with or knowledge of [syn:
       disavowal, disclaimer]

The Free On-line Dictionary of Computing (19 January 2023):

disclaimer

    Statement ritually appended to many Usenet
   postings (sometimes automatically, by the posting software)
   reiterating the fact (which should be obvious, but is easily
   forgotten) that the article reflects its author's opinions and
   not necessarily those of the organisation running the computer
   through which the article entered the network.

   [Jargon File]

   (1995-07-30)


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

disclaimer
 n.

    [Usenet] Statement ritually appended to many Usenet postings (sometimes
    automatically, by the posting software) reiterating the fact (which should
    be obvious, but is easily forgotten) that the article reflects its author's
    opinions and not necessarily those of the organization running the machine
    through which the article entered the network.