@Jmartusewicz, as for meaning - I don't know, but maybe it comes from the Latin name Martinus (English: Martin). The ending "-ewicz" suggests Eastern origin:
https://polishforums.com/language/ethnic-backround-suffixes-surnames-72736/
So, Martusewicz could mean "a son of Martin", for example.
Also, it seems there's a possibility that you can have noble roots (but only genealogical research could confirm that) - your surname is connected to one of the oldest Polish coat of arms called Łabędź (Swan), which was also adopted by Lithuanian boyars:
pl.m.wikipedia.org/wiki/%C5%81ab%C4%99d%C5%BA_(herb_szlachecki)
In English:
en.m.wikipedia.org/wiki/%C5%81ab%C4%99d%C5%BA_coat_of_arms
https://polishforums.com/language/ethnic-backround-suffixes-surnames-72736/
From what I've read suffixes like -icz, -owicz, -ewicz denote Eastern origin, namely - Ukraine or Belarus.
They were often connected to a father's first name (so it was a kind of "son of"
They were often connected to a father's first name (so it was a kind of "son of"
So, Martusewicz could mean "a son of Martin", for example.
Also, it seems there's a possibility that you can have noble roots (but only genealogical research could confirm that) - your surname is connected to one of the oldest Polish coat of arms called Łabędź (Swan), which was also adopted by Lithuanian boyars:
pl.m.wikipedia.org/wiki/%C5%81ab%C4%99d%C5%BA_(herb_szlachecki)
In English:
en.m.wikipedia.org/wiki/%C5%81ab%C4%99d%C5%BA_coat_of_arms