principles.fyi · the brain · concept

polysemy

When one word carries several different meanings.

one word -> many meanings (e.g. "mouse" = animal or device)

Polysemy is the fact that a single word often has multiple meanings — 'mouse' the animal vs. the computer device, 'light' as in weight vs. brightness. It's the reason a single fixed embedding per word is fundamentally limited: that one vector has to be a compromise across every sense. Because contextual embeddings shift with the sentence, an encoder can split a polysemous word into the right meaning on the fly.