What is Public Officer?

Legal Definition
An officer of a public corporation ; that is, one holding office under the government of a municipality, state, or nation. In English law, an officer appointed by a joint-stock banking company, under the statutes regulating such companies, to prosecute and defend suits in its behalf. For definitions of the various classes and kinds of officers, see the titles "Commissioned Officers," "Executive," "Fiscal," "Judicial," "Legislative," "Ministerial," "Municipal," "Non-Commissioned," "Peace," and "State."
-- Black's Law Dictionary
Legal Definition
Any man having any duty concerning the public. See 63 Am. St. Rep. 182, note.
-- Ballentine's Law Dictionary