D defs.my
Entry 2 senses Webster, 1913

Hall-mark

/(ha̤l"märk`)/ · Hall·-mark · IPA
01 n. The official stamp of the Goldsmiths' Company and other assay offices, in the United Kingdom, on gold and silver articles, attesting their …
  1. 1.
    The official stamp of the Goldsmiths' Company and other assay offices, in the United Kingdom, on gold and silver articles, attesting their purity.
  2. 2.
    A distinguishing characteristic or characteristics; as, a word or phrase lacks the hall-mark of the best writers.[figuratively]