Pronunciation: /ˈpɛt.rɪ.kɔːr/ Part of speech: noun Definition: The distinctive, pleasant, earthy scent that rises from dry soil or rock when rain begins to fall on it. Etymology: <cite index="3-2">The term was coined in 1964 by Australian scientists Isabel Joy Bear and Richard G. Thomas of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), derived from the Greek words *petra* (πέτρα), meaning "stone," and *ichor* (ἰχώρ), the ethereal fluid said to flow in the veins of the gods in Greek mythology.</cite> <cite index="6-9">Thomas coined the term to refer to what had previously been known as "argillaceous odour."</cite> The *petra* root is also an etymological relative of words like *petrify* and *petroleum*, while ichor carries its mythological weight from ancient Greek poetry and epic tradition. Synonyms: argillaceous odour, rain scent, geosmin aroma, earth fragrance, pluvial scent, rain smell In a sentence: After weeks of summer drought, the first drops hit the cracked sidewalk and released a wave of petrichor_ so rich it stopped her mid-stride.