I know what "macro" photography is in general terms: close-up shots where the subject is captured in "life size" or at some magnification factor greater than 1:1. What I don't quite follow is what lens characteristics qualify it to be called a "Macro" lens? With my previous (all point & shoot) digital cameras, the macro mode allowed them to focus at ridiculously close distances (e.g., my Konica-Minolta Z5 could focus as close as about 2" from the subject in good light).
As an example, I have what I believe is a Soligor (the lens itself doesn't have a name on it, but the matching case does) 135mm F2.8 that's got MACRO engraved on the front bezel:
It seems to take fairly good pictures (as good as my limited manual focusing skills allow), even in not-so-great light, but can't focus on anything closer than about 4-5 feet away.
The real question is that I don't quite understand what makes it a Macro? Can anyone explain this to a neophyte like me?