Enigma comes from a Greek word that means "to speak in riddles." It applies to things, as well as to people, that puzzle one's mind. Egypt's ancient pyramids and quantum mechanics, for example, might be described as enigmas, as well as physicist Stephen Hawking. In these uses, the word's meaning is a figurative extension of the original "riddle" sense.

Are you an enigma?

A person who is described as an enigma is a bit of a mystery. You never know what that person is really thinking, or what his or her motives for doing something are. An enigma is not easily understood especially because he or she has a confusing mixture of qualities that seem to be in opposition to one another—for example, the attention-seeking but reclusive musician, or the brilliant lawyer who gets lost on the drive home from the grocery store.

The word enigma originally referred not to people but to words, and specifically to words that formed a riddle or complicated metaphor that tested the listener's or reader's alertness and cleverness. This meaning is clearly connected to the word's history. Enigma comes from a Greek word that means "to speak in riddles."

The word enigma didn't jump from referring to riddles to referring to people. In between those uses, it was (and still is) applied to things that puzzle people. Egypt's meticulously constructed Pyramids of Giza or a theory of quantum physics, for example, might be described as enigmas. In these uses, the meaning is simply a figurative extension of the original "riddle" sense.