Ajar is not synonymous with “a jar.” This just goes to prove that nothing (i.e., a space) can be something. Consider that to be a topic for philosophical discussion and get back to me with your comments.
Instead, the word ajar means slightly open. So, for example, if you were to twist the lid of a jar so that the lid is sitting lose and hanging slightly off the side jar, without removing the lid completely, the jar lid would be ajar. Consider that to be serendipitous nonsense and get back to me with your comments.