The Collaborative International Dictionary of English v.0.48:

Pd \Pd\ prop. n.
   The chemical symbol for palladium, an element of the
   platinum group, of atomic number 46.

   Syn: palladium.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Pd
    n 1: a silver-white metallic element of the platinum group that
         resembles platinum; occurs in some copper and nickel ores;
         does not tarnish at ordinary temperatures and is used
         (alloyed with gold) in jewelry [syn: palladium, Pd,
         atomic number 46]

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

PD
       Plug & Display [standard] (LCD, VESA), "P&D"


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

PD
       Packetization Delay


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

PD
       Public Domain


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

PD
 /P?D/, adj.

    [common] Abbreviation for ?public domain?, applied to software distributed
    over Usenet and from Internet archive sites. Much of this software is not
    in fact public domain in the legal sense but travels under various
    copyrights granting reproduction and use rights to anyone who can snarf a
    copy. See copyleft.


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

public domain
PD
public domain software

   (PD) The total absence of copyright protection.  If
   something is "in the public domain" then anyone can copy it or
   use it in any way they wish.  The author has none of the
   exclusive rights which apply to a copyright work.

   The phrase "public domain" is often used incorrectly to refer
   to freeware or shareware (software which is copyrighted
   but is distributed without (advance) payment).  Public domain
   means no copyright -- no exclusive rights.  In fact the phrase
   "public domain" has no legal status at all in the UK.

   See also archive site, careware, charityware,
   copyleft, crippleware, guiltware, postcardware and
   -ware.  Compare payware.