A brainiac is a very intelligent person.

// Her ability to solve almost any puzzle within minutes secured her place as the brainiac of the family

Paradigm is a formal word that refers to a pattern or example, and especially to an outstandingly clear or typical example or archetype. It can also refer to a theory or group of ideas about how something should be done, made, or thought about.

// Her latest book provides us with a new paradigm for modern biography.

// Several speakers at the conference focused their presentations on challenging what has been a dominant educational paradigm.

Unbeknownst means “without being known about by (a specified person or group of people).”

// Unbeknownst to the students, the teacher had entered the room.

When used literally, lodestone refers to the mineral magnetite, a magnetic iron ore. Lodestone is also used figuratively to refer to something that, like a magnet, strongly attracts things.

// The city is a lodestone for aspiring musicians of all genres.

Efficacious is a formal word used to describe something—often a treatment, medicine, or remedy—that has the power to produce a desired result or effect.

// Companies like to tout the number of efficacious natural ingredients in their beauty products.

1. fundamentally different or distinct in quality or kind

2. including markedly dissimilar elements

To foment something, such as hostility or opposition, is to cause it, or try to cause it, to grow or develop. Foment is used synonymously with incite.

// Rumors that the will was a fake fomented distrust between the two families.

Consternation is a formal word that refers to a strong feeling of surprise or sudden disappointment that causes confusion.

// The candidate caused consternation among his supporters by changing positions on a key issue.

When you go incognito, your true identity is kept secret (as through the use of a different name or a disguise). Incognito can be used either as an adverb or an adjective with the same meaning.

// The food critic made an incognito visit to the restaurant.

// The pop star travels incognito as much as possible, using a fake name and wearing a wig and heavy makeup to avoid the paparazzi.

To gossip is to talk about the personal lives of other people.

// The two siblings often gossip with each other about their neighbors via texting.