Compounds of 不易

• 不易
  (adj-na,n) constancy
  immutable
• 千古不易
  (n) eternally unchanging
• 不易流行
  (exp) the principle of fluidity and immutability in haiku
  Haiku is both "fluid and transitory" and "eternal and immutable."
  An interchange between the transient and the immutable is central to the soul of haiku. (Basho)
• 万古不易
  (n) eternally unchanging
• 万世不易
  (n) eternity
  perpetuity
• 万代不易
  (adj-na,n) eternity
  perpetuity