Word
Chirality
Handedness: the property of a shape that cannot be made to match its mirror image by turning it
Examples
The crystals' chirality helped explain why their solutions rotated polarized light in opposite directions.
A left-handed glove is a useful model of chirality: turning it does not make it right-handed.
Origin
Chirality comes from the Greek word for hand. The physicist Lord Kelvin named the property in the nineteenth century, decades after Louis Pasteur's crystal work. The name captures a geometric distinction: a reflected form may be similar without being superposable.
How it connects
The word makes the difference between resemblance and superposition precise.
This word appeared in The difference a mirror makes, the Involves connection for September 11, 2026, which asked: How can the same ingredients produce two different shapes?
Check yourself
Which object is a useful everyday example of chirality?
A glove made specifically for the left hand. Exactly. A left-handed glove and its reflection cannot be made identical through rotation alone.
What the sources establish
Chirality means non-superposability on a mirror image; the hand-derived name was introduced by Kelvin after Pasteur's work.
Sources
Chirality (International Union of Pure and Applied Chemistry), Gold Book entry C01058: geometric definition
Mirror Life: Inside the Discussion (Institut Pasteur), Historical introduction: Pasteur's demonstration and Kelvin's later terminology