The Collaborative International Dictionary of English v.0.48:

Elm \Elm\, n. [AS. elm; akin to D. olm, OHG. elm, G. ulme, Icel.
   almr, Dan. & Sw. alm, L. ulmus, and E. alder. Cf. Old.]
   (Bot.)
   A tree of the genus Ulmus, of several species, much used as
   a shade tree, particularly in America. The English elm is
   Ulmus campestris; the common American or white elm is U.
   Americana; the slippery or red elm, U. fulva.
   [1913 Webster]

   Elm beetle (Zo["o]l.), one of several species of beetles
      (esp. Galeruca calmariensis), which feed on the leaves
      of the elm.

   Elm borer (Zo["o]l.), one of several species of beetles of
      which the larv[ae] bore into the wood or under the bark of
      the elm (esp. Saperda tridentata).

   Elm butterfly (Zo["o]l.), one of several species of
      butterflies, which, in the caterpillar state, feed on the
      leaves of the elm (esp. Vanessa antiopa and Grapta
      comma). See Comma butterfly, under Comma.

   Elm moth (Zo["o]l.), one of numerous species of moths of
      which the larv[ae] destroy the leaves of the elm (esp.
      Eugonia subsignaria, called elm spanworm).

   Elm sawfly (Zo["o]l.), a large sawfly (Cimbex Americana).
      The larva, which is white with a black dorsal stripe,
      feeds on the leaves of the elm.
      [1913 Webster]

WordNet (r) 3.0 (2006):

elm
    n 1: any of various trees of the genus Ulmus: important timber
         or shade trees [syn: elm, elm tree]
    2: hard tough wood of an elm tree; used for e.g. implements and
       furniture [syn: elm, elmwood]

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

ELM
       ELectronic Mailer (Unix)


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

elm

    A full-screen MUA for Unix, MS-DOS, MS
   Windows, and OS/2.

   Usenet newsgroup: news:comp.mail.elm.

   FAQ
   (http://cis.ohio-state.edu/hypertext/faq/usenet/elm/FAQ/faq.html).

   (1996-03-20)


Easton's 1897 Bible Dictionary:

Elm
   Hos. 4:13; rendered "terebinth" in the Revised Version. It is
   the Pistacia terebinthus of Linn., a tree common in Palestine,
   long-lived, and therefore often employed for landmarks and in
   designating places (Gen. 35:4; Judg. 6:11, 19. Rendered "oak" in
   both A.V. and R.V.). (See TEIL TREE.)