Meaning of maco
- In the very distant past, maco, originally "chubby," became an alternative cover-up name for "bear." Here are some details:
As to madzo, it might have come about as an unexpected/misspelled version of maco, but in case the -z- had a diacritic in Slovak (madz~o), the names maco and madz~o would probably not be related.
Gres~ is probably a shorter version of Gres~o, which, in turn, was a version of Gregor (like Greg - Gregory in English).