A nickname for this name is Betty, both in English and Greek (pronounced beh-TEE in Greek (although the b makes a sort of combination v/b sound)). I don't have any idea how it's spelled, though, because I've never seen it written down in Greek. My grandma tells me it used to be very common, and I have a great aunt called this, but I've never heard it on a younger person so I'd guess it's a bit dated, like Betty is in English.