A “potent” drug is one that is very strong. The “potent” root comes from the Latin for “able to do” or “powerful” as found in other English words like “potentate,” “potency,” and “potential.” Efficacy is the ability to produce a given result. (Think of it as meaning, “Able to produce a given effect”). Something that is impotent is lacking in efficacy. When someone dithers, he or she delays making a decision. Such a person could be said to lack “resolution,” which means “a firm resolve to do something.”

A discourteous person does not show courtesy or politeness. Thus, the analogy could be written as, “As someone who is discourteous is lacking in politeness, so is something nugatory lacking in X.” The word “nugatory” comes from the Latin for “trifles” or “small worthless things.” It is not the same as nougat, which is a tasty and nutty treat. Thus, something “nugatory” is merely trifling, that is lacking value.

Something that is safe lacks danger. Thus, this analogy could be rewritten, “As something safe lacks danger, so does a wakeful state lack X.” When someone is wakeful, he or she either does not need sleep or cannot do so. Likewise, the word can be used to describe a period of time as in “a wakeful night.” In the latter case, it means “a night passed without sleep.” The word “sleep” is the best option for that which is lacking in wakefulness.

Something that is impregnable is unable to be broken or destroyed. For instance, an “impregnable fortress” is one believed to be completely safe and unable to be overcome. Such a thing lacks any weakness. Thus, the analogy could be written, “As something impregnable lacks weakness, something flaccid lacks X.” Something flaccid is soft, loose, or flabby. Such a thing lacks firmness.

A deterrent is something that instills doubt regarding a possible course of action. For instance, one could say, “The thought of the cold weather was a deterrent against running outside, and Peter decided to stay inside with a warm cup of coffee instead.” Thus, the analogy could be rewritten as “A deterrent is meant to discourage as a revelation is meant to X.” Although the word “revelation” is often used in religious contexts, particularly Christian ones speaking of the “Book of Revelation” in the Bible, it means “the making known of something that had been secret.” (It is—unsurprisingly—related to “reveal”). A revelation is meant to disclose some previously unknown fact.

When something occurs “intermittently,” it happens in a way that is not regular. While a clock ticks regularly, the dripping of a faucet occurs intermittently without any pattern. Thus, the analogy could be written, “As something intermittent is characterized by irregularity, so is a steadfast person characterized by X.” When a person is steadfast, he or she is devoted in a faithful and unwavering manner. Such a person is characterized by loyalty, which is the best option among those provided.

"Dishonest" and "upright" are strong antonyms; similarly an anotnym of "studious" is "ignorant."

"Rigid" and "flaccid" are total opposites, just as an antonym for "coarse" is "delicate."

"Abundant" is the opposite of "scarce," as are "garngantuan" and "miniscule" antonyms.

"Composed" and "agitated" are antonyms, as are "urgent" and "unimportant."