constancy

Noun

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

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

• the quality of being enduring and free from change or variation
  • early mariners relied on the constancy of the trade winds
    

Related words

• Synonyms: 
  perceptual constancy , stability
• Antonyms: 
  inconstancy , changefulness