What is Certificate?

Legal Definition
Practice. A writing made in any court, and properly authenticated, to give notice to another court of anything done therein; or it is a writing by which an officer or other person bears testimony that a fact has or has not taken place.

2. There are two kinds of certificates; those required by the law, and those which are merely voluntary. Of the first kind are certificates given to an insolvent of his discharge, and those given to aliens, that they have been naturalized. Voluntary certificates are those which are not required by law, but which are given of the mere motion of the party. The former are evidence of the facts therein mentioned, while the latter are not entitled to any credit, because the factscertified, may be proved in the usual way under the solemnity of an oath or affirmation. 2 Com. Dig. 306; Ayl. Parerg. 157; Greenl. Ev. 498.
-- Bouviers Law Dictionary
Legal Definition
A written assurance or official representation, that some act has or has not been done or some event occurred or some legal formality been complied with. Particularly, such written assurance made or issuing from some court, and designed as a notice of things done therein or as a warrant or authority, to some other court, judge or officer. People v. Foster, 27 Misc. Rep. 576, 58 N. Y. Supp. 574; U. S. v. Ambrose, 108 U. S. 336, 2 Sup. Ct. 682, 27 L. Ed. 746; Ti-conic Bank v. Stackpole, 41 Me. 305. A document in use in the English customhouse. No goods can be exported by certificate, except foreign goods formerly imported, on which the whole or a part of the customs paid on importation is to be drawn back, Wharton.
See also
-- Black's Law Dictionary
Legal Definition
A signed statement by an officer giving authenticity to the facts therein set forth. See 27 Misc. Rep. 576, 58 N. Y. Supp. 574.
-- Ballentine's Law Dictionary