Today’s find ✦
Petrichor
/ˈpet.rɪ.kɔːr/
After rain on dry earth
Caused by geosmin + plant oils
Coined 1964
OED entry 2000
Detectable at 5 parts per trillion
Humans evolved to smell it from miles away
Illustration
Ancient Greek landscape · rain on warm stone
steam rising · golden late-afternoon light
— Canva / DALL-E prompt ready
Ancient Greek landscape · rain on warm stone
steam rising · golden late-afternoon light
— Canva / DALL-E prompt ready
14 sections · ~11 min read
01Definition⌃
The pleasant smell produced when rain falls on dry earth.
More precisely: the scent released when rain hits warm, dry ground — caused by plant oils absorbed into soil during drought, combined with geosmin produced by soil bacteria. One of those things everyone has experienced and almost no one had a name for until 1964.[1]Bear & Thomas (1964). Nature, 201, 993–995. Open source ↗
02How to remember it⌃
The hook
petra = stone · ichor = the fluid in the veins of the gods
So: divine blood on stone. Rain on dry earth. Once you know that, the word becomes the smell.
So: divine blood on stone. Rain on dry earth. Once you know that, the word becomes the smell.
Visual
petra (stone) + ichor (divine fluid) = petrichor
simple illustrated equation · Canva
petra (stone) + ichor (divine fluid) = petrichor
simple illustrated equation · Canva
“She stepped outside after the first rain in weeks and breathed in the petrichor — that specific, irreplaceable smell that meant summer was finally breaking.”
— original example
“The petrichor hit him before he reached the door — that ancient smell, as though the ground itself had been waiting.”
— original example
03The phrase⌃
“the smell of petrichor”
Technically redundant — petrichor is already a smell — but it works as a kindness to readers still learning the word. Once they know it, “the petrichor rose from the ground” is better.
“The first drop hit the pavement and immediately the smell of petrichor rose around her — that ancient, specific smell she had waited all summer for without knowing it had a name.”
Why “rose” works: petrichor doesn’t fall from above, it rises from below. The verb carries the direction.
“Petrichor — coined in 1964 by Bear and Thomas to name the scent of rain on dry earth. From Greek petra (stone) and ichor (the fluid that flows in the veins of the gods). One of the few scientific coinages beautiful enough to escape the journal that published it.Bear & Thomas, Nature, 1964 — full entry in Sources below”
Use it
04Use it right⌃
“The petrichor rose from the garden as she walked past.”
Clean, specific, correct. Petrichor = the smell. Rising from the ground = right direction.
“She loved the smell of petrichor after a long dry summer.”
“The smell of petrichor” is technically redundant but widely used and immediately clear.
“The petrichor fell from the clouds.”
Petrichor rises from the earth, it’s not carried by rain. The rain triggers it; petrichor is what comes up in response.
“I love the petrichor before a storm.”
What you smell before a storm is ozone — not petrichor. Petrichor is released when rain hits dry ground, so it happens after rain starts, not before.
Try it yourself
Complete this sentence using petrichor correctly:
After three weeks without rain, the first drops finally fell and
filled the air.
“the smell of petrichor” or just “petrichor” — filled the air. Both work.
05Check your knowledge⌃
Petrichor — quiz
3 questions
Before we start — how well did you know this word before reading this entry?
Question 1 of 3
What does petrichor specifically refer to?
Option C is ozone — that pre-storm smell from lightning ionizing the air. Petrichor is what happens after rain hits dry ground, not before.
Question 2 of 3
Which sentence uses petrichor correctly?
A: petrichor rises from ground, not falls from clouds. B: petrichor needs rain to hit dry earth first. D: petrichor requires dry earth, not ocean.
Question 3 of 3
Petrichor comes from two Greek words. What are they?
The same petra in Peter, petrified, petroleum. Ichor was the immortal fluid in the veins of the Greek gods. Rain on stone, divine blood on earth.
3/3
You know petrichor
Ready to use it in the right context next time you step outside after rain.
The details
06Quick facts⌃
1
You can detect geosmin (the compound that causes petrichor) at five parts per trillion — more sensitive than a shark detecting blood. Your nose is extraordinarily tuned to this specific smell.[3]Scientific American — What Causes the Smell of Fresh Rain? Open source ↗
2
Petrichor was coined in 1964 but didn’t reach the OED until 2000 — 36 years later. Most scientific coinages never escape the journal. This one did because it was too precise and too beautiful not to.[2]Oxford English Dictionary — petrichor, n. (2000). Open source ↗
3
Some evolutionary biologists believe humans evolved such sensitivity to geosmin because it signaled approaching rain — meaning water and vegetation nearby. The smell may have mattered for survival. That might explain why it feels like something beyond just a smell.
4
The other smell described in Bear and Thomas’s 1964 paper was “argillaceous odour” — the smell of wet clay. That phrase did not travel. Petrichor won because it was poetic. Names matter even in science.
07Grammar and usage⌃
Part of speech
Noun
Uncountable — “the petrichor” or “a smell of petrichor”, never “a petrichor”
Related forms
petrichor (n only)
“petrichoral” appears occasionally online but is not established
Common pairing
“smell of petrichor”
Also: “the petrichor rose”, “breathed in the petrichor”
Register
Formal / Literary
Understood by most educated readers. In casual speech it will earn a look.
Tip
“The petrichor” alone is enough once your reader knows the word. “The smell of petrichor” is redundant but works as an introduction.
08Word family⌃
The name Peter comes from the same Greek root — Jesus called Simon “Petros” (the Rock). So petrichor, petrified, petroleum, and one of the twelve apostles all share the same stone.
09The origin story⌃
Visual · Timeline
Ancient Greece → 1964 Australia → 2000 OED
illustrated map · Canva
Ancient Greece → 1964 Australia → 2000 OED
illustrated map · Canva
GR
Ancient Greek
petra
Stone, rock. Root of “petrified,” “petroleum,” and the name Peter. One of the oldest Greek words for solid earth.
GR
Ancient Greek mythology
ichor
The ethereal fluid in the veins of the gods — immortal, golden, not blood. Homer used it in the Iliad. The word had been largely dormant in English for centuries before 1964.
1964
English · coined 1964
petrichor
Two Australian geologists — Isabel Joy Bear and R.G. Thomas — published a paper in Nature identifying the compounds behind the smell of rain on dry earth. They reached into Greek mythology and pulled out something perfect. The paper was titled “Nature of Argillaceous Odour.” That title is forgotten. The word is not.[1]Bear & Thomas (1964). Nature, 201, 993–995. Open source ↗
OED
Oxford English Dictionary · 2000
officially recognized
36 years after coinage. By then petrichor had already escaped scientific literature entirely and was appearing in novels, poems, and everyday speech. People needed it before the dictionary caught up.
The world
10Context⌃
Science
Chemistry: Geosmin + petrichor oil released when raindrops hit dry earth. The chemistry is elegant. The name is more so.
Writing
Literature: Before 1964, writers described it as “the smell of rain” or “that earthy scent.” Petrichor gave them precision. You can feel the relief in contemporary prose when the word appears.
Psych
Memory: Smell connects most directly to memory and emotion. Petrichor is almost universally associated with strong place-memories. The word unlocks something people didn’t know they were carrying.
Online
When it escaped: Petrichor spread online in the mid-2000s. The reaction was near-universal: “I knew this smell. I had no idea it had a word.” That recognition — I felt this and now it exists — is what the best vocabulary words do.
11Not to be confused with⌃
Petrichor is specific to dry earth after rain. There are several closely related but distinct smells that people often mix up with it.
Component
Geosmin
The compound produced by soil bacteria that makes up part of petrichor. Geosmin is the chemistry; petrichor is the experience.
Often confused
Ozone
The electric metallic smell before a thunderstorm is ozone — not petrichor. Petrichor happens after rain hits earth. Ozone happens before, from lightning ionizing the air.
Broader
“Smell of rain”
Petrichor is specific to dry earth. Rain on pavement, leaves, or ocean is not petrichor. The word earns its precision.
12Related words⌃
Sonder
Wistful
Both are words for things everyone has felt and almost no one had named. Petrichor opens the senses; sonder opens the imagination. They arrive the same way — unexpectedly.
Ephemeral
Poetic
Petrichor is ephemeral by nature — it exists for minutes, then passes. The smell is bittersweet because it can’t stay.
Hiraeth
Melancholy
Petrichor is one of the smells most associated with hiraeth — a longing for somewhere the smell takes you. Where that is differs for everyone.
Geosmin
Reflective
The compound inside the smell. Geosmin is the science; petrichor is the poetry. Knowing both changes how you experience a summer storm.
Go further
13FAQ⌃
Why does rain smell so good? ⌃
Two reasons working together. Geosmin — produced by soil bacteria — has an intensely earthy, almost sweet smell that humans detect at extraordinarily low concentrations. Petrichor oil — secreted by plants during drought and absorbed into soil — adds a second layer when released by rain. Together they create something that feels ancient, which it is: some evolutionary biologists believe we’re so sensitive to these compounds because they signaled water and vegetation to early nomadic populations. The smell may have mattered for survival.
Is petrichor a real word? ⌃
Yes — coined by scientists in a 1964 Nature paper and in the OED since 2000. Not slang, not internet-invented. A properly formed scientific coinage that escaped into general use.
How do you pronounce petrichor? ⌃
/ˈpet.rɪ.kɔːr/ — PET-ri-kor. Stress on the first syllable. The “ch” is a hard k sound from the Greek ichor, not a “ch” as in “chair.”
What exactly causes petrichor? ⌃
Two things: geosmin (produced by Streptomyces bacteria in soil) and petrichor oil (secreted by plants during drought, absorbed into soil and rock). When rain hits dry ground, both release into the air. Your nose detects geosmin at five parts per trillion.
14Related reading⌃
Origins · Language history
How does a word get into the dictionary?
Petrichor took 36 years. Some words take longer. Some never make it. The OED process is more interesting than you’d expect.
Word entry · Science
Geosmin — the compound inside the smell
From geo (earth) + osme (smell). The chemistry underneath the poetry. You can detect it at five parts per trillion.
Word entry · Mythology
Ichor — what flows in the veins of the gods
Still exists in English as a medical term. The divine connotation didn’t survive, but the word did.
Not the same thing
Ozone — the smell before the storm
The electric smell before rain is ozone from lightning. Understanding the difference makes both words more precise.
Sources
Primary source
Bear, I.J. & Thomas, R.G. (1964). “Nature of Argillaceous Odour.” Nature, 201, 993–995. ↗
Further reading
Scientific American — What Causes the Smell of Fresh Rain? ↗
See something wrong? Suggest a correction →
Read next
Sonder
The realization that each stranger has a life as vivid as your own.
Both are words for things you felt before you could name them.
Ephemeral
Lasting a very short time. Beautiful because it ends.
The smell of petrichor lasts minutes. Ephemeral is the word for that.
Hiraeth
A Welsh longing for home that can’t be returned to.
Petrichor is one of the smells most associated with hiraeth.