Etymology tree
Proto-Iranian *wardahder.?
Ancient Greek ῥόδον (rhódon)bor.?
Latin rosalbor.
Old French rose
Latin -ittus
Old French -ete
Old French rosetebor.
Old Galician-Portuguese roseta
Portuguese roseta
Inherited from Old Galician-Portuguese roseta, borrowed from Old French rosete, from rose + -ete.
By surface analysis, rosa + -eta.