Steadfastness, as in purpose or affection; faithfulness.(noun)
The condition or quality of being constant; changelessness.(noun)
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 "constancy" in a sentence
"Such constancy is predicated upon the utter hopelessness of his love."
"Returning to the inevitable unfolding of things is called constancy"
"The visual representation of constancy is found in the slowly animating photographic image of our male "stand in" for Blake, which in the first two stanzas is semi-transparently mapped onto the walls of London."