The Collaborative International Dictionary of English v.0.48:

Cameronian \Cam`e*ro"ni*an\, n.
   A follower of the Rev. Richard Cameron, a Scotch Covenanter
   of the time of Charles II.
   [1913 Webster]

   Note: Cameron and others refused to accept the "indulgence"
         offered the Presbyterian clergy, insisted on the Solemn
         league and Covenant, and in 1680 declared Charles II.
         deposed for tyranny, breach of faith, etc. Cameron was
         killed at the battle of Airdmoss, but his followers
         became a denomination (afterwards called Reformed
         Presbyterians) who refused to recognize laws or
         institutions which they believed contrary to the
         kingdom of Christ, but who now avail themselves of
         political rights.
         [1913 Webster]