How does a nonsense syllable differ from an ordinary word, and why did Ebbinghaus use them?

A nonsense syllable is a meaningless letter cluster (like WID or ZOF) with no prior associations — Ebbinghaus used them to measure "pure" memory uncontaminated by existing knowledge.

If Ebbinghaus had memorized real words, his results would have been distorted by what he already knew — some words are vivid, familiar, or emotionally charged, and would stick better for reasons unrelated to raw memory. By inventing syllables with no meaning, he tried to give every item an equal, neutral starting point. The trade-off is realism: real learning almost always leans on meaning and connection, so his curve represents a deliberately stripped-down, worst-case picture of retention.