The hallmark of something or someone is their most typical quality or feature.
例句
It's a technique that has become the hallmark of Amber Films...這已經成為安伯電影公司的標志性技術。The killing had the hallmarks of a professional assassination...這起謀殺案具有職業暗殺的特征。
N-COUNT
（金、銀、鉑制品上標明純度、產地、制造者的）印記
A hallmark is an official mark put on things made of gold, silver, or platinum that indicates the quality of the metal, where the object was made, and who made it.