hallmark

Short definition from Wiktionary

Noun

1. 1
   A distinguishing characteristic.
2. 2
   An official marking made by a trusted party, usually an assay office, on items made of precious metals.

Verb

1. 1
   To provide or stamp with a hallmark.

Proper noun

1. 1
   A surname.
2. 2
   Ellipsis of Hallmark Cards.