Meaning

noun the quality of being enduring and free from change or variation

noun (psychology) the tendency for perceived objects to give rise to very similar perceptual experiences in spite of wide variations in the conditions of observation

noun faithfulness and dependability in personal attachments (especially sexual fidelity)

originEtymology tree Latin cōnstantiabor. English constancy Borrowed from Latin cōnstantia.

Etymology from Wiktionary, CC BY-SA 3.0