Meaning of “hallmark” - Learner’s Dictionary

hallmark

noun [ C ] uk us /ˈhɔːlmɑːk/
OFFICIAL

an official mark that is put on something made of silver or gold to prove that it is real

TYPICAL

a quality or method that is typical of a particular type of person or thing:

Simplicity is a hallmark of his design.

(Definition of “hallmark” from the Cambridge Learner’s Dictionary © Cambridge University Press)