n.1 a a person's name, initials, or mark used in signing a letter, document, etc. b the act of signing a document etc.
2 archaic a distinctive action, characteristic, etc.
3 Mus. a key signature. b time signature.
4 Printing a a letter or figure placed at the foot of one or more pages of each sheet of a book as a guide for binding. b such a sheet after folding.
5 US directions given to a patient as part of a medical prescription.
Phrases and idioms:
signature tune esp. Brit. a distinctive tune used to introduce a particular programme or performer on television or radio.
Etymology: med.L signatura (LL marking of sheep), as SIGNATORY