from
The Collaborative International Dictionary of English v.0.48
Protestant \Prot"es*tant\, n. [F. protestant, fr. L. protestans,
-antis, p. pr. of protestare. See {Protest}, v.]
One who protests; -- originally applied to those who adhered
to Luther, and protested against, or made a solemn
declaration of dissent from, a decree of the Emperor Charles
V. and the Diet of Spires, in 1529, against the Reformers,
and appealed to a general council; -- now used in a popular
sense to designate any Christian who does not belong to the
Roman Catholic or the Greek Church.
[1913 Webster]