Here's why it's unusual:
* "Bi" means two. So, "bi-semester" might suggest two semesters. However, we already have the term "semester" which represents a six-month period of study.
* "Semester" is already a division. A semester is a well-established division of the academic year. There's no need to further divide it.
If you're looking for a term to describe two semesters, the best options are:
* Academic year: This covers the entire period of study in a school year (typically two semesters).
* Two semesters: This is the most straightforward and clear way to refer to the period of study.
It's possible "bi-semester" is a word someone has created or used in a specific context, but it's not a common or accepted term. If you encountered this word, it's best to ask for clarification or look for a more standard alternative.