constancy

noun

the quality of being enduring and free from change or variation
耐久性があり、変化や変動のない性質
- early mariners relied on the constancy of the trade winds
  昔の船員は、貿易風の不変性に頼った
faithfulness and dependability in personal attachments (especially sexual fidelity)
個人的な愛情において忠実で信頼できる（とくに性的な信頼）
the tendency for perceived objects to give rise to very similar perceptual experiences in spite of wide variations in the conditions of observation
観測の状態が多様であるにもかかわらず、認識された物体が、とてもよく似た知覚体験をもたらすという傾向