Not true to duty or obligation; disloyal.(adjective)
Having no religious faith.(adjective)
Unworthy of faith or trust; unreliable.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "faithless" in a sentence
"Occasionally, what's called a faithless elector votes for somebody else."
"Throughout U.S. history there have been numerous cases of so - called faithless electors who changed their minds."
"Therefore it is more fitting that you should be called faithless than that the Moors should be."