"Parasol" was not accepted as a translation of şemsiye, although that is technically the most accurate translation. Is şemsiye regularly used for a rain umbrella rather than yağmurluk? (I am thinking of the difference in German between Sonneschirm and Regenschirm). I realize that Turkey's climate is different from northern Europe, so perhaps the distinction may be unimportant there.
If you allow I will play guessing, as Turkish is my weaker side. Şems is sun when translating from Arabic. But in Turkish sun is guneş. And on google translate "parasol" is Guneş şemsiyesi. I mean, for me, there is sense to say guneş şems... for parasol. Sorry if I am wrong.