blouse n. 1. A woman's or child's loosely fitting shirt that extends to the waist or slightly below. See Note at greasy. 2. A loosely fitting garment resembling a long shirt, worn especially by European workmen. 3. The service coat or tunic worn by the members of some branches of the US armed forces. intr. & tr.v. bloused, blous·ing, blous·es To hang or cause to hang loosely and fully.
[French, possibly alteration (influenced by blousse, wool scraps, of Germanic origin) of obsolete French blaude, from Old French bliaut, probably of Germanic origin .]
sweatshirt n. A usually long-sleeved, collarless, oversize pullover made traditionally of heavy cotton jersey that has a fleeced backing.
you should consider the fact that Polish changed since you were growing up. 1950s dictionary agrees with what you think http://sjp.pwn.pl/doroszewski/bluza;5413875.html
Modern dictionary- not so much http://www.wsjp.pl/index.php?id_hasla=396ind=0w_szukaj=bluza
and google image results for bluza http://imgur.com/tsU1ygU