Histories

The standard form of this name in Polish is Rozmarynowski, but it makes perfect sense that it could come to be spelled the way you write it in English. The -owski is properly pronounced "off-skee" in Polish, but in many parts of the country they barely pronounce that "ff" sound, so that it comes out more like "-ah-skee." Thus Rosemarynoski is a pretty good way of writing how Rozmarynowski sounds to those of us used to English phonetic values. The root of the name is rozmaryn, the Polish word for the herb "rosemary" (both English and Polish get this word from Latin rosmarinus). The surname, like all names ending in -ski, is an adjective, meaning literally "of, from, pertaining to the __ of rosemary," where you fill in the blank with something implied and understood, something that doesn't need to be said. It could be "kin," it could be "place." So the surname could mean "of, from, pertaining to the kin of Rosmaryn," with that used as a first name. This seems possible because there is also a surname Rozmarynowicz, "son of Rozmaryn," so this may have been used as a first name. But more likely in most cases is that the surname means "person from Rozmarynowo," where that is the name of a village, literally "the place of rosemary," i.e., a place where there was a lot of rosemary around. Most surnames are at least a couple of centuries old, and many, many surnames refer to places that have since changed names or disappeared, etc. But it makes sense that a person or family who came from this place (and possibly others too small to show up in my sources) known for its rosemary might come to be called Rozmarynowski, i.e., "one from Rozmarynowo" = "one from the place of rosemary."