What is the meaning of notional?

adjective

• Not based on fact; unreal.
  • usage: "the falsehood about some fanciful secret treaties- F. D. Roosevelt; "a small child's imaginary friends"; "to create a notional world for oneself"
  • synonyms: fanciful, imaginary
• Not based on fact or investigation.
  • usage: "a notional figure of cost helps in determining production costs"; "speculative knowledge"
  • synonyms: speculative
• Indulging in or influenced by fancy.
  • usage: "a fanciful mind"; "all the notional vagaries of childhood"
  • synonyms: fanciful
• Being of the nature of a notion or concept.
  • usage: "a plan abstract and conceptional"; "to improve notional comprehension"; "a notional response to the question"
  • synonyms: conceptional, ideational