The pleasant, earthy smell after rain falls on dry soil.

Origin: The word 'petrichor' was coined in the 1960s by Australian researchers Isabel Joy Bear and R. G. Thomas. It combines the Greek word 'petra' (meaning 'stone') and 'ichor', which in Greek mythology refers to the fluid that flows in the veins of the gods. Historical and Cultural Context: First introduced in a scientific paper in 1964, 'petrichor' describes the distinctive scent released when rain hits dry earth. The scent is due to a combination of plant oils and the chemical compound geosmin, produced by soil-dwelling bacteria. Evolution: The term has remained relatively stable in its use since its inception, with few phonetic or semantic shifts. It has been embraced by various cultures to describe the universal experience of this scent. Modern Relevance: Today, 'petrichor' is used widely in literature and conversation to evoke nostalgia and a connection to nature. It's often referenced in descriptions of rural settings and during discussions of weather phenomena.

The compound geosmin, responsible for the smell of petrichor, is so potent that humans can detect it at concentrations as low as five parts per trillion!