Lexical Compendium

Jevons Paradox is the economic principle stating that as technological improvements increase the efficiency of resource use, overall consumption of that resource may increase rather than decrease.

Originally observed by 19th-century economist William Stanley Jevons in relation to coal consumption during the Industrial Revolution, the paradox highlights how greater efficiency lowers costs, which can drive higher demand.

Jevons Paradox was in the news a lot early in 2025 after the unveiling of AI models developed by a Chinese start-up called DeepSeek. In a report titled "DeepSeek-V3 Technical Report" published in December, DeepSeek showed that they were able to create this AI model much more efficiently (and cheaper) than their counterparts (i.e. OpenAI's ChatGPT, Meta's Llama, etc).

AI research benefits from more efficient neural networks, yet Jevons Paradox suggests that these efficiency gains will lead to even greater overall computational demand, as more complex models are developed and deployed at scale.

While all of this was in the news, Microsoft's Satya Nadella posted on X: Jevons paradox strikes again! As AI gets more efficient and accessible, we will see its use skyrocket, turning it into a commodity we just can't get enough of.

Kayfabe is the convention of presenting staged performances as genuine or authentic. The word is used primarily in the world of wrestling, but it is also used more generally to just mean a fake presentation. I heard the word being used in the context of politics to describe President Trump and lying.

The exact etymology of the word is uncertain, but there are theories that it is slang (perhaps somewhat Pig Latin-ized) for "be fake." ^[2]

From Wikipedia:

The Leahy Laws or Leahy amendments are U.S. human rights laws that ostensibly prohibit the U.S. Department of State and Department of Defense from providing military assistance to foreign security force units that violate human rights with impunity.

In 2024, as the Israel–Hamas war wages on, the Leahy Law has been in the news a lot.

A leitmotif is a recurring theme, idea, or motif that runs through a work, often associated with a particular character, concept, or situation. The term originates from German Leitmotiv, meaning "leading motif" and was used to describe Wagner's characteristic association of a melody to a character.

I was introduced to this term while watching Music by John Williams. In the documentary, George Lucas describes how he wanted John to create a theme for each of the characters in Star Wars.

In simple terms, the longer something is around, the better it gets (or the longer it's likely to continue to be around).

I first heard a reference to this in a Breaking Points episode in which the hosts were debating the merits of lab grown meat.

The origin of this term comes from a 1964 article published in The New Republic by Albert Goldman. In this article, Goldman described comedians that used to meet up at Lindy's Deli in NYC discussing comedy shows. An observation was made that the longer a show has been running, the longer it is expected to continue to run. This was formalized in something Goldman called "Lindy's Law." Note: this is also commonly referred to as the "Lindy Effect."

Do you have the habit of expressing a positive statement by negating its opposite (or vice-versa)? For example, saying something is "Not bad" when you mean that it's good?

This is called a litotes (pronounced LIE-tuh-teez). The word comes from the Greek lítotēs, meaning simplicity. Litotes can be used to soften something, i.e. saying "I'm not bad at this" seems less boastful than saying "I'm pretty good at this." It can also be used for humorous effect, for example saying "I don't hate it!" instead of saying that you like something.

I ran across the idiom loma abajo y sin frenos in an SNL sketch ^[1] about kids in a Spanish class.

It's a Cuban idiom that literally translates to "downhill without brakes." It is used to describe something that has gone "out of control," but is usually used in a romantic context to describe completely falling for someone (Me tienes loma abajo y sin frenos -- "You have me downhill and with no brakes").

I could not find the origin of this idiom.

The lysine contingency is intended to prevent the spread of the animals in case they ever got off the island. Dr. Wu inserted a gene that creates a single faulty enzyme in protein metabolism. The animals can't manufacture the amino acid lysine. Unless they're continually supplied with lysine by us, they'll slip into a coma and die. --Ray Arnold, Jurassic Park

When I was a kid I read Jurassic Park multiple times. I loved that book.

The Lysine Contingency is a made up concept in the novel Jurassic Park by Michael Crichton and is defined in the quote above. I think it could perhaps be used more generically to describe a deliberately engineered dependency on a single critical input, intended to constrain or control a system’s behavior. I've been thinking about this as it relates to AI and guardrails.

Update August 2026: I re-read Jurassic Park. Still such a great book. Having watched the movie multiple times since I last read the book as a kid, I was struck by how different the Dr. Alan Grant character is in regards to his relationship to children. In the movie he's portrayed as a person who doesn't necessarily enjoy children (at first anyway). In the book he's described as someone who likes children from the very beginning (the book explicitly notes that it is impossible not to like kids who are openly enthusiastic about dinosaurs).

A metonymy is a figure of speech in which a word or phrase is substituted with another closely associated with it. For example, in the sentence "Hey, who are all the suits?" the word suit is a metonymy for "business people."

The word comes from the Greek metōnymía, meaning "a change of name."

I heard the word in an episode of PBS' Otherwords.

Mice lie and monkeys exaggerate.

-- David B. Weiner, Ph.D. Professor, Department of Pathology and Laboratory Medicine Chair, Gene Therapy and Vaccine Program, CAMB Co-Leader Tumor Virology Program, Abramson Cancer Program University of Pennsylvania, Perelman School of Medicine

Dr. Weiner coined this aphorism while musing on the use of NHP (nonhuman primates) in HIV vaccines studies at a conference in 2008. In essence, animal models aren't necessarily predictive of how drugs will work in humans.

The phrase is often used in research papers and by science journalists. I can't recall where I first heard it, but I thought of it recently when a friend shared a blurb about how rapamycin is purported to have anti-aging benefits in humans. Though there is no evidence for this in humans, there have been studies with the drug on mice that have found that they live ~12% longer.