Main Entry:

touch·stone

Pronunciation:

\ˈtəch-ˌstōn\

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