Original and primordial describe something relating or belonging to the earliest stages of a thing’s existence. Original suggests something as it first was, at the beginning of its existence, often in contrast to what succeeds it: her original hair color; the original purpose of the law. It usually refers to existences within human history, while primordial suggests something existing at the very beginning of much older, prehistoric things, usually formed by natural and physical processes, such as the primordial atmosphere of Earth, which no longer exists, and human beings’ primordial instincts, which have existed since the beginning. The well-known expression, “primordial soup,” actually illustrates a different definition of the word, which refers to something that is itself the origin. The soup is the mixture of chemicals hypothesized to have given rise to life on earth.

Both words refer to displaying the facial expression that indicates pleasure, amusement, scorn, or mockery. On its own, smile commonly suggests such an expression indicating pleasure or amusement: smiled and waved, but in context, it can refer to a contemptuous expression, more like a sneer. To simper is to indicate pleasure by one’s expression, but in a silly, self-conscious, or ingratiating way: a salesperson simpering at customers. The situation in which simper is used is often that of flirtation or trying to win favor. Simper is found in the company of words like “sweet,” “cloying,” and “fawning,” which emphasize the fake, coy, or servile nature of such smiling—at least to the eye-rolling observer.

Both words describe the state of mental confusion and surprise prompted by an encounter with something we don’t understand or can’t make sense of. The familiar adjective puzzled refers to the effect on us of something we don’t understand: She looked puzzled. Nonplussed refers to a greater degree of confusion, combined with surprise, that may render a person temporarily speechless and slightly disoriented: Her sudden about-face on this issue left her supporters nonplussed. It is common for someone to be left nonplussed or be nonplussed to discover, find, or learn something. Typically, someone can be, seem, or look nonplussed, be left nonplussed by something, or wear a nonplussed expression or stare. However, it’s also common for someone to be in this state only momentarily or for a moment.