noun a chief notary or clerk.
2. protonotary ·noun ·same·as prothonotary.
3. protonotary ·noun the chief secretary of the patriarch of constantinople.
4. protonotary ·noun a register or chief clerk of a court in certain states of the united states.
5. protonotary ·noun formerly, a chief clerk in the court of king's bench and in the court of common pleas, now superseded by the master.
6. protonotary ·noun formerly, one who had the charge of writing the acts of the martyrs, and the circumstances of their death; now, one of twelve persons, constituting a college in the roman curia, whose office is to register pontifical acts and to make and preserve the official record of beatifications.