Vestigial

Today's Word Vestigial veh-STIJ-ee-uhl Definition (adjective) Remaining as a small or incomplete part of something that was once much larger or more developed. Example The cave fish have vestigial eyes that no longer function in complete darkness. Word Origin Late 18th century: from Latin vestigium meaning “footprint” or “trace.” Fun Fact Vestigial is often used in biology to describe body parts that have lost their original function—like the human appendix, tailbone, or wisdom teeth. But the word also works metaphorically: a vestigial tradition might survive long after its meaning has faded. It’s a favorite in evolutionary science, architecture, and even fashion—where tiny flourishes hint at functions once essential, now mostly symbolic.

Apocryphal

Today's Word Apocryphal uh-POK-ruh-fuhl Definition (adjective) Of doubtful authenticity, although widely believed to be true. Example The story of Einstein failing math as a child is entirely apocryphal. Word Origin Late 16th century: from ecclesiastical Latin apocryphalus, from Greek apokruphos ‘hidden’, from apokruptein ‘to hide away’. Fun Fact Apocryphal is often used to describe myths, urban legends, and viral stories that sound believable—but fall apart under scrutiny. The word was originally used to describe religious texts that were excluded from the official Bible due to doubtful origins. Today, you’ll find it in journalism, education, and pop culture critique—anywhere facts are murky and stories stick around despite being debunked.

Mercurial

Today's Word Mercurial mur-KYOOR-ee-uhl Definition (adjective) Subject to sudden or unpredictable changes of mood or mind. Example Her mercurial temperament made collaboration both exciting and exhausting. Word Origin Mid 17th century: from Latin mercurialis ‘relating to the god Mercury’, known for his speed and unpredictability. Fun Fact Mercurial originally referred to qualities associated with Mercury, the Roman messenger god—quick, clever, and elusive. Today, the word is often used to describe emotionally volatile people, though it can also apply to markets, creative energy, or political behavior. In psychology, a mercurial personality isn’t just moody—it’s brilliant, erratic, and hard to pin down.

Sanguine

Today's Word Sanguine SANG-gwin Definition (adjective) Optimistic or hopeful, especially in a difficult situation. Example Despite the company setbacks, the CEO remained sanguine about the future. Word Origin Middle English: from Old French sanguin(e), from Latin sanguineus ‘of blood’ — originally referring to the belief that a person’s blood temperament made them cheerful. Fun Fact Historically, sanguine was one of the four “humors” in ancient medicine. People with a sanguine temperament were believed to be cheerful, sociable, and energetic, thanks to an abundance of blood in their system. Today, the word is still used to describe people who remain confident and upbeat, especially when others are panicking. It’s a subtle way to say, they’re keeping it together—even when things look bleak.

Inure

Today's Word Inure ih-NUR Definition (verb) To become accustomed to something, especially something unpleasant. Example Over time, she became inured to the constant noise of the city. Word Origin Late Middle English: from Old French enurer, based on Latin inurare — in- (into) + urere (to burn), originally meaning “to burn in” or “harden by fire.” Fun Fact Inure often describes the mental or emotional process of adapting to difficulty, stress, or discomfort. It’s frequently used in psychology, journalism, and military contexts—anywhere people learn to cope with harsh conditions. You might become inured to cold weather, online trolling, or even tragic news headlines. It’s a word that suggests resilience—but also desensitization.

Deleterious

Today's Word Deleterious del-uh-TEER-ee-uhs Definition (adjective) Causing harm or damage, often in a subtle or unexpected way. Example Prolonged exposure to stress can have deleterious effects on your health. Word Origin Mid 17th century: from medieval Latin deleterius, from Greek dēlētērios ‘noxious’, from dēlētērios (related to destroy or *to hurt’). Fun Fact Deleterious is often used when something appears harmless but turns out to be damaging—like sugary drinks, misinformation, or prolonged noise. It’s not the loud crash—it’s the slow rot. You’ll find it in medical journals, legal decisions, and HR handbooks. It’s a favorite when talking about effects that are subtle, cumulative, and serious—without sounding dramatic.

Perfidious

Today's Word Perfidious per-FID-ee-uhs Definition (adjective) Deceitful and untrustworthy; deliberately disloyal. Example His perfidious actions during the negotiation shocked even his rivals. Word Origin Late Middle English: from Old French perfidieux, from Latin perfidiosus, from perfidia ‘treachery’, based on per- ‘through’ + fides ‘faith’. Fun Fact Perfidious isn’t your average insult. It suggests a deep and knowing betrayal, often by someone who pretended to be loyal. Historically, it was used in diplomacy and politics—perfidious Albion was a nickname used by the French to accuse Britain of double-dealing. It shows up in literature, courtroom speeches, and bitter breakups. This isn’t just someone who disappointed you—it’s someone who knew exactly what they were doing.

Sinuous

Today's Word Sinuous SIN-yoo-uhs Definition (adjective) Having many curves and turns; lithe and graceful in movement. Example The sinuous path through the forest twisted like a river. Word Origin Mid 17th century: from Latin sinuosus, from sinus meaning “a bend” or “curve.” Fun Fact Sinuous doesn’t just describe shape—it often implies beauty, fluidity, or grace in motion. You’ll find it used to describe snakes, rivers, dancers, or even sentence structure. In design, a sinuous form can be elegant or hypnotic. In literature, it’s often paired with movement—like a sinuous melody, path, or gesture that draws the eye without abruptness.

Irascible

Today's Word Irascible ih-RASS-uh-buhl Definition (adjective) Easily provoked to anger; quick-tempered. Example His irascible demeanor made every team meeting tense. Word Origin Late Middle English: from Old French irascible, from late Latin irascibilis, from irasci ‘grow angry’. Fun Fact Irascible doesn’t always describe someone in a full-on rage—it can apply to people who are just easily irritated or constantly on edge. It’s often used in fiction to characterize grumpy older men, volatile bosses, or that one short-fused coach. Think Scrooge, Dr. House, or a chihuahua with something to prove. It’s a word that paints a personality in tension.

Fallacious

Today's Word Fallacious fuh-LAY-shus Definition (adjective) Based on a mistaken belief or containing logical errors. Example Her argument was persuasive but ultimately fallacious. Word Origin Late 15th century: from Latin fallaciosus, from fallere, meaning “to deceive.” Fun Fact Fallacious is the go-to word for arguments that sound solid at first—until you scratch the surface. It’s often used in logic, law, and debate to call out flawed reasoning, like straw man arguments or false dilemmas. In politics, marketing, and social media, fallacious reasoning spreads fast, which is why the word often shows up in fact-checking articles. It’s not about lying outright—it’s about logic that doesn’t hold up.