Intransigent is a formal word that describes a person who refuses to compromise or abandon an often extreme position or attitude. It can also describe a thing, such as a system or point of view, that shows the same kind of stubbornness.

// Despite the mediator's best efforts, the opposing sides in the dispute remained intransigent.

Zest refers to an enjoyably exciting quality, or to keen enjoyment itself. In culinary use, zest refers to small pieces of the peel of a lemon, lime, orange, or other citrus fruit used as flavoring.

// His humor added zest to the presentation's admittedly dry material.

// The couple has a zest for travel and adventure.

// Lime zest adds a burst of brightness to the dessert's rich flavor.

Fugacious is a formal word that describes something that lasts only a short time.

// The rock band’s early success proved fugacious; within two years its members had moved on to other careers.

// Savor the enduring pleasures of life as intensely as the fugacious ones.

A rendition, simply put, is the act or result of rendering something. That thing may be a performance or interpretation, a depiction, or a translation. In US law, rendition refers to the surrender by a state of a fugitive to another state that is charging the fugitive with a crime.

// Their signature meatloaf is a fine rendition of a classic recipe.

// Theatergoers have been eager for an English rendition of the acclaimed French play.

Taciturn is a formal word that describes someone who tends to be quiet or who tends to speak infrequently.

// One of the twins was taciturn and shy, while the other one was more outgoing.

Numinous is a formal, often literary, word that typically describes things that have a mysterious or spiritual quality. It can also describe something holy or something that appeals to one's aesthetic sense.

// We were overcome by the numinous atmosphere of the catacombs.

// The artist's sculptures dominate the space, their numinous presence welcoming museum-goers to a foreign world.

To coruscate is to give off or reflect light in bright beams or flashes. Coruscate is used as a synonym of sparkle and may also be used to mean "to be brilliant or showy in technique or style."

// She placed a bid on a classic car from the 1950s, replete with yards of coruscating chrome.

Exorbitant describes something that goes far beyond what is fair, reasonable, or expected (as by being too high, too expensive, etc.).

// The cost of our stay was so exorbitant you would have thought that we had bought the hotel and not just spent a few nights there.

to consider or include something as part of a more comprehensive one

impassable

Something described as gossamer—such as a butterfly wing or a thin fabric—is very light or delicate.

// Except for a few gossamer clouds, the sky was clear and blue.

To fret is to worry or be concerned.

// I was sure we wouldn’t get there in time, but they told me not to fret.

Chthonic means "of or relating to the underworld." It is used as a synonym of infernal.

// Cleo compared entering her brother's basement bedroom to a descent into chthonic regions: it was dark and odd-smelling, and she was a little frightened of what she might find there.

Feckless describes people or things that are weak or ineffective.

// The agency’s response to the dramatic increase in air pollution was well-intentioned but ultimately feckless.

If something written, spoken, or otherwise communicated is described as lucid, it is very clear and easy to understand. A person described as lucid is able to think clearly. Lucid is also used to describe things that are luminous, or that are visually transparent.

// The film conveyed a lucid message that was hard to misinterpret. // Brenna marveled at the sea stars and urchins she could see through the lucid water of the rock pool.

To deter someone is to discourage or prevent them from acting. To deter a thing is to stop or limit it.

// The heavy fines aim to deter people from dumping garbage here.

// The device is designed to deter automobile theft.

Jerkwater means “remote and unimportant.” It is often used to describe a small town, village, etc., that is out in the country far from cities. Jerkwater can also mean “trivial.”

// I grew up in a jerkwater town in the middle of nowhere.

To rue something is to feel penitence, remorse, or regret for it. Rue is often used in the phrase "rue the day."

// I rue the day I signed that infernal contract.

Heinous describes things—such as acts, deeds, or crimes—that are hatefully or shockingly evil, or in other words, deserving of hate or contempt.

// The former dictator will stand trial for the role he played in his government’s heinous treatment of political dissidents.

Approbation is a formal word that refers to praise or approval.

// Their plan to rewild portions of the city’s parks has won the approbation of the mayor.

By and large is another way of saying "in general" or "on the whole."

// By and large, I like the way things have gone.

The word dally has a number of meanings. To dally can be to physically linger or dawdle, or to waste time. Dally may also mean "to act playfully," especially in a romantic sense, or "to deal with something lightly or in a way that is not serious."

// Three members of the hiking group were dallying and didn't arrive at the overlook until others were already starting to head back to the trailhead.

// Alton has been dallying with the idea of starting a bakery.

A nebula is a large cloud of interstellar gas or dust. In nontechnical use, the word nebula also refers to a galaxy other than the Milky Way.

// We were eventually able to see the nebula through the telescope.

Liminal is a formal word most often used to describe an intermediate state, phase, or condition. It can also describe something that is barely perceptible or barely capable of eliciting a response.

// The essay presents an image of the border region as a liminal zone where one culture blends into another.

Callow is a synonym of immature used to describe someone, especially a young person, who does not have much experience and does not know how to behave like an adult. Like the word immature, callow is often used disapprovingly.

// The novel’s plot involves a callow youth who eventually learns the value of hard work and self-reliance.

To fraternize with someone is to be friendly with them or to spend time with them in a friendly way. Fraternize is often, though not always, used in situations where such friendly behavior is considered wrong or improper, as in “fraternizing with the enemy.”

// The boss warned that fraternizing with the junior employees could be a risky career move for a manager.

Something described as chockablock is very full or tightly packed.

// Their mantel is chockablock with knickknacks collected from their travels to all fifty states.

Someone described as ambivalent has or displays very different feelings (such as love and hate) about someone or something at the same time.

// Aya was ambivalent about starting her first year away at college—excited for the new opportunities that awaited but sad to leave her friends and family back home.

Memento is a synonym of souvenir; it refers to something that is kept as a reminder of a person, place, or thing.

// The box on the shelf in her closet is filled with mementos of her basketball career—awards, newspaper clippings, team photographs, and her old uniform.

close in time; about to occur

A gridiron is a football field. The word gridiron is also sometimes used to refer to a grate for broiling food (as in “put the steaks on the gridiron”) or something consisting of or covered with a network (as in “a gridiron of streets and avenues”).

// The book recounts the quarterback’s most glorious moments on the gridiron.

Someone or something ensconced is firmly placed or hidden. Ensconce can be a synonym of shelter and conceal, or of establish and settle.

// The sculpture is safely ensconced behind glass.

// He ensconced himself in the library's back room for the afternoon.

Cronyism is the unfair practice by a powerful person (such as a politician) of giving jobs and other favors to friends without regard for their qualifications.

// City residents are pushing back against cronyism and corruption in their local government.

Something described as Byzantine (or Byzantine) is very complicated, secret, and hard to understand. In its most literal (and always capitalized) sense, Byzantine describes that which is "of, relating to, or characteristic of the ancient city of Byzantium."

// The company's byzantine accounting practices have gotten it into trouble with the government.

// Works of Byzantine art filled the gallery's walls.

Clement is a formal word used to describe weather that is mild, or in other words, neither too hot nor too cold. Clement is also sometimes used to describe someone who is inclined to be merciful or lenient, as in “a clement judge.”

// Although she loves visiting the northeast, Sue prefers to live in places with a more clement climate, without heavy snows or high heating bills.

To lollygag is to spend time doing things that are not useful or serious, or in other words, to fool around and waste time.

// Stop lollygagging and get to work!

// The player was kicked off the team for lollygagging during practice.

Propinquity is a formal word that typically refers to nearness in place or time, making it a synonym of proximity. It can also be used as a synonym of kinship to refer to the state of being related to others by blood.

// The geographical propinquity of these ancient cultures explains many of the architectural similarities.

Fallacious is a formal word that typically describes something, such as an argument or assumption, that is false or inaccurate and that tends to mislead or deceive others. // The notion that disease is caused by malign spirits was known to be fallacious long before the advent of germ theory.

Jeremiad refers to a long cautionary or angry rant about something. It can also refer to a similarly prolonged lamentation, or expression of great sorrow or deep sadness.

// His jeremiad about trivial problems with the campsite didn’t go over well with his friends.

In general contexts, something that ossifies becomes hardened or conventional and opposed to change. In medical contexts, something that ossifies (such as cartilage) forms or is transformed into bone.

// I asked if she'd reconsider her position, but her opinions on the matter have clearly ossified.