touchstone
n.a standard or test that helps you judge the quality or value of something. You use it to compare a new thing to a well-known example.
n.a standard or criterion used to evaluate or judge the quality, authenticity, or value of something. Often used metaphorically to describe a benchmark against which other works or ideas are measured.
“The new movie is a touchstone for modern horror films.”
“The critic argued that the novel serves as a touchstone for the entire genre, influencing every writer that followed.”
“While the artist's early works were experimental, his later pieces became the touchstone for the movement, defining its aesthetic and technical standards for decades.”
“Therefore, whether paleobotanists can find fossils resembling free carpels has become a touchstone for these botanists.”
“During this time he chalked up a remarkable record as a dissident from his party’s frontbench policy on a wide range of leftwing touchstone issues.”
From touch + stone.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.