What is Declare?

Legal Definition
To make known or publish. By tho constitution of the United States, congress have power to declare war. In this sense the word, declare, signifies, not merely to make it known that war exists, but also to make war and to carry it on. 4 Dall. 37; 1 Story, Const. §428; Rawle on the Const. 109. In pleading, to declare, is the act of filing a declaration.
-- Bouviers Law Dictionary
Legal Definition
To solemnly assert a fact before witnesses, e. g., where a testator declares a paper signed by him to be his last will and testament. Lane v. Lane, 95 N. Y. 498. This also is one of the words customarily used in the promise given by a person who is affirmed as a witness,—"sincerely and truly declare and affirm." Hence, to make a positive and solemn asseveration. Bassett v. Denn, 17 N. J. Haw, 433. With reference to pleadings, it means to draw up, serve, and file a declaration ; e. g., a "rule to declare." Also to allege in a declaration as a ground or cause of action; as "he declares upon a promissory note."
-- Black's Law Dictionary
Legal Definition
To set forth in a declaration.
-- Ballentine's Law Dictionary