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

Sed

    Stream editor.

   The Unix stream editor.  It has a powerful but cryptic
   command language and is based on regular expressions.

   There is a GNU version called GNU Sed.

   [Jargon File]

   (1994-11-03)


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

smoke-emitting diode
SED

    (From "light-emitting diode") An
   incorrectly connected diode, probably a light-emitting
   diode, in the process of losing its magic smoke and
   becoming a friode.

   See also LER.

   (1996-04-28)


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

SED
 /S·E·D/, n.

    [TMRC, from ‘Light-Emitting Diode’] Smoke-emitting diode. A friode that
    lost the war. See also LER. [Not to be confused with sed(1), the Unix
    stream editor. —ESR]