Confederate, n.
1. One who is united with others in a league; a person or a nation engaged in a confederacy; an ally; also, an accomplice in a bad sense. He found some of his confederates in gaol. Macaulay.
2. (Amer. Hist.)
A name designating an adherent to the cause of the States which attempted to withdraw from the Union (1860-1865).
3 other Webster entries under this spelling
Confederate, a.
1. United in a league; allied by treaty; engaged in a confederacy; banded together; allied. All the swords In Italy, and her confederate arms, Could not have made this peace. Shak.
2. (Amer. Hist.)
Of or pertaining to the government of the eleven Southern States of the United States which (1860-1865) attempted to establish an independent nation styled the Confederate States of America; as, the Confederate congress; Confederate money.
Confederate, v. t. [imp. & p. p. Confederated; p. pr. & vb. n. Confederating.]
To unite in a legue or confederacy; to ally. With these the Piercies them confederate. Daniel.
Confederate, v. i.
To unite in a league; to join in a mutual contract or covenant; to band together. By words men . . . covenant and confederate. South.
Shades of meaning
Fernald has no entry of its own for confederate; he lists it under accessory, associate, auxiliary.
Where he writes about it:
Colleague is used always in a good sense, associate and coadjutor generally so; ally, assistant, associate, attendant, companion, helper, either in a good or a bad sense; abetter, accessory, accomplice, confederate, almost always in a bad sense. — from accessory