Wow, straight people using "semi-bi" to fit in? Yikes.
Semi means half. Bi means two sexes. For "bi" to be true, you must still hold an attraction to both sexes. If you're semi-bi it means to me that you have a partial attraction for both.
If you take the distributive property of Semi (meaning half) to the concept of sexual preference (1/2 female + 1/2 Male) we can rewrite that as (.5f + .5m), then apply the semi (again meaning half) the equation looks like .5(.5f+.5m)=SP (sexual preference). It then becomes that we have (.25f + .25m)=SP.
Meaning you're semi bisexual and you're partially attracted to males and females, while what else you're attracted to is undefined. As I said in my greeting post, I endorse self-determination. I believe "semi-bi" is a thing, just not in the context which people claim to be using it. Straight =/= semi bi.
There are also people who are attracted to inanimate objects. However, I don't have any personal experience or expertise on the matter to opine on that situation. It is my goal, however, to always increase my understanding for all people from all walks of life... I've spent over a year here conversing with MAGA trying to understand their mental context. Well. It didn't take long. My error was trying to find more answers in that mess than there were.