What is the meaning of interchangeable?

adjective

• Mathematics, logic. ( such that the arguments or roles can be interchanged)
  • usage: "the arguments of the symmetric relation, `is a sister of,' are interchangeable"
• Capable of replacing or changing places with something else; permitting mutual substitution without loss of function or suitability.
  • usage: "interchangeable electric outlets" "interchangeable parts"
  • synonyms: exchangeable, similar, standardized, standardised