An analogy is a similarity between like features of two things, on which comparison may be based. For instance, you might see an analogy, or similarity, between the heart and a pump. The word analogy also refers to a comparison based on such similarities—a favored tool of writers and poets since time immemorial. Consider the following passage from the novel The Conspirators by Alexandre Dumas: “her beauty, her grace, her elegance, even her talents were but an accident—an error of nature—something like a rose flowering on a cabbage stock.” The part about being a rose on a cabbage stock is in itself an analogy insofar as it is a comparison. But that sense of analogy is not quite synonymous with similarity (bear with us!). The similarity in this passage is that of being accidental or out of place, referring to the woman and the rose.

The adjective healthy gets a lot of use this time of year as so many of us resolve to eat healthy foods and embrace a healthy lifestyle in the new year. Robust is a synonym for healthy, but it is not used to describe food or behaviors that are conducive to good health. Robust emphasizes strength and vigor and is used to describe people that are in particularly fine fettle. It’s also used to describe markets or economies that are thriving or are especially resilient, and discussions or debates that are especially productive or spirited and engaging. You may even hear of a robust password or a robust method, each being strong and effective in all of most situations.

The adjective opposite is used to describe things that are opposed or are radically different from each other. Antithetical describes things that are diametrically opposed. The latter is a more pointed and precise adjective, and it is commonly used to highlight essential incompatibilities between ideas, behaviors, or values. For instance, if words or deeds are or are perceived as antithetical to democratic principles, then they go (or are perceived to go) against those principles starkly and irreconcilably.