n.
Pronunciation: ' t ə ch- ˌ st ō n
Function: noun
Date: 1530
1 : a black siliceous stone related to flint and formerly used to test the purity of gold and silver by the streak left on the stone when rubbed by the metal
2 : a test or criterion for determining the quality or genuineness of a thing
3 : a fundamental or quintessential part or feature : BASIS <a touchstone film of that decade> <now considered a touchstone of the city's life ― Michael Specter>
synonyms see STANDARD