Mythology is the "study (logia) of myths (mythos)", it has Greek origins. Myths do not necessarily mean false or imaginary, it means stories, legends, folklore, tradition, etc. So it should be used for asking questions about stories/tales that are part of Hindu tradition, custom and beliefs.
Mythology is not just about imaginary stories but can be real stories of people in the ancient times. E.g., Itihasas (Ramayana and Mahabharata) are ancient histories or Vedic mythology, and they are not necessarily imaginary.