Which word is most similar in meaning to "pictograph"?

The term "pictograph" refers to a symbol that visually represents an idea or concept, often through imagery rather than words. It primarily relies on illustrative images to convey information. Therefore, the most similar word in meaning is "symbol," as both words relate to representations that carry significance beyond just the visual aspects.

The other options, while related in some capacity to illustrations or visual representation, don't align as closely with the specific nature of a pictograph. "Illustration" generally refers to a drawing or picture used to explain something but does not have the inherent symbolic aspect that a pictograph carries. "Diagram" refers to a drawing or plan that outlines components or processes, which is more technical and less abstract than a pictograph. On the other hand, a "chart" is a systematic arrangement of data, typically used for comparison or analysis, and lacks the direct symbolic representation found in pictographs.