Both verbs refer to keeping something from happening. Prevent, the more neutral of the two, suggests keeping something from even starting, or employing measures in advance to do so: prevent forest fires. Thwart, which comes from the Old Norse word meaning “across” or “traverse,” suggests a more dramatic interruption of something in process—especially someone’s efforts or plans—before it can reach its goal: thwarted the plot; thwart an alien invasion.

Both nouns refer to the phenomenon or experience of being naturally drawn to a person, thing, or idea. Attraction suggests a desire to get closer to the object, which, for things and ideas, may mean acquiring, adopting, or studying the object. Because talking about an attraction to a person is usually taken to mean a romantic or sexual interest, it’s useful to have affinity at your disposal. Affinity suggests a phenomenon in which a person feels a natural liking toward another person or thing, often based on a recognition of similarity or empathy with them. If a student demonstrates an affinity for lab research, they’re not only interested in it but well-suited to it, and take to it fairly quickly. Someone might possess an affinity with a foreign culture if they have already formed a set of interests and sympathies that are a natural fit.

Both words refer to something that slows, prevents, or stops progress. When we encounter an obstacle, we are at least temporarily stopped in our tracks until we figure out a way to overcome the obstacle. Hindrance refers to something that interferes with progress—slows it down or makes it more difficult—but doesn’t necessarily bring things to a complete halt. Lack of money might be an obstacle to getting a college education. A job that helps pay for your education may become a hindrance to your studies because of the time and energy the job requires. You may have to decide whether the job is, in the common expression, more of a hindrance than a help.