Real Dictionary

ideogram
countable noun: An ideogram is a sign or symbol that represents a particular idea or thing rather than a word. The writing systems of Japan and China, for example, use ideograms.
countable noun: In languages such as English which are written using letters and words, an ideogram is a sign or symbol that can be used to represent a particular word. %, @, and & are examples of ideograms.

ideogram in American English
a graphic symbol representing an object or idea without expressing, as in a phonetic system, the sounds that form its name
noun: a written symbol that represents an idea or object directly rather than a particular word or speech sound, as a Chinese character

ideogram in British English
noun: a sign or symbol, used in such writing systems as those of China or Japan, that directly represents a concept, idea, or thing rather than a word or set of words for it