The Collaborative International Dictionary of English v.0.48:

Ideogram \I*de"o*gram\, n. [Ideo- + -gram; cf. F. id['e]ograme.]
   1. An original, pictorial element of writing; a kind of
      hieroglyph expressing no sound, but only an idea.
      [1913 Webster]

            Ideograms may be defined to be pictures intended to
            represent either things or thoughts.  --I. Taylor
                                                  (The
                                                  Alphabet).
      [1913 Webster]

            You might even have a history without language
            written or spoken, by means of ideograms and
            gesture.                              --J. Peile.
      [1913 Webster]

   2. A symbol used for convenience, or for abbreviation; as, 1,
      2, 3, +, -, ?, $, ?, etc.
      [1913 Webster]

   3. A phonetic symbol; a letter.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ideogram
    n 1: a graphic character that indicates the meaning of a thing
         without indicating the sounds used to say it; "Chinese
         characters are ideograms" [syn: ideogram, ideograph]

Moby Thesaurus II by Grady Ward, 1.0:

88 Moby Thesaurus words for "ideogram":
   allegory, alphabet, arrowhead, art, blueprint, character,
   charactering, characterization, charactery, chart, choreography,
   cipher, conventional representation, conventional symbol,
   cuneiform, dance notation, delineation, demonstration,
   demotic character, depiction, depictment, determinative, diagram,
   drama, drawing, emblem, exemplification, figuration, grammalogue,
   hieratic symbol, hieroglyph, hieroglyphic, hieroglyphics, hiragana,
   iconography, iconology, ideograph, illustration, imagery, imaging,
   kana, katakana, letter, limning, logogram, logograph, logotype,
   love knot, map, musical notation, notation, ogham, phonetic,
   phonetic symbol, pictogram, pictograph, picturization, plan,
   portraiture, portrayal, prefigurement, presentment, printing,
   projection, radical, realization, rendering, rendition,
   representation, rune, schema, score, script, shorthand, syllabary,
   symbol, symbolic system, symbolism, symbolization, symbology,
   tablature, token, totem, totem pole, type, wedge, word letter,
   writing



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

ideogram

    A symbol representing a concept.  Nearly all
   ideograms are pictograms - pictures of the thing represented,
   others are merely conventional.  An example of non-pictorial
   ideogram might be the degree symbol (a superfix circle) when
   used for temperature.

   (2014-07-30)