Definitions of notional:

• adjective:   having descriptive value as distinguished from syntactic category

  Example: "Sex is a notional category"

• adjective:   not based on fact or investigation

  Example: "A notional figure of cost helps in determining production costs"

• adjective:   indulging in or influenced by fancy

  Example: "All the notional vagaries of childhood"

• adjective:   being (or being of the nature of) a notion or concept

  Example: "To improve notional comprehension"

• adjective:   not based on fact; dubious

  Example: "To create a notional world for oneself"