I. ˈhȯl-ˌmärk noun
Etymology: Goldsmiths' Hall, London, England, where gold and silver articles were assayed and stamped
Date: 1721
1.
a. : an official mark stamped on gold and silver articles in England to attest their purity
b. : a mark or device placed or stamped on an article of trade to indicate origin, purity, or genuineness
2. : a distinguishing characteristic, trait, or feature
the dramatic flourishes which are the hallmark of the trial lawyer — Marion K. Sanders
II. transitive verb
Date: 1773
: to stamp with a hallmark