touchstone
/ˈtʌtʃ.stoʊn/
noun
Origin
English
touch + stone — a stone for testing
Overview
Meaning Now
- A dark, fine-grained stone (such as basanite or jasper) used to test the purity of precious metals by observing the color of the streak they leave when rubbed against it.
- A standard or criterion by which the quality, performance, or authenticity of something is judged.
Literal older meaning
A stone used to 'touch' or test the surface of gold or silver.
Language path
Old French → Middle English → English
Earliest form
touch-stone
Earliest period
16th century
Journey
In ancient times, a streak from a gold sample on a touchstone was compared to needles of known gold purity. The colors, influenced by the alloy composition, indicated the approximate gold content. This literal test became a common metaphor in literature for any standard used to verify true value.
Evolution
- Middle English
touchen
“to test, to strike”
Derived from Old French 'tuchier'.
- 16th century
touchstone
“Lydian stone used for testing gold”
Compound formation combining the act of testing with the material.
- 17th century
touchstone
“metaphorical standard of judgment”
Extended from the metallurgical process to abstract quality assessment.
Connections
Word parts
touch
root
to test by physical contact
stone
root
mineral object
Related across languages
French
pierre de touche
touchstone
Related words
Explore next
Related to touchstone
External references use DefinedTerm semantics.