The small orange-red fruit that forms on rose bushes after the flowers, with a mass of seeds and irritating hairs inside. It is usually sold dried, cut and seeded, for steeping as a tart fruit tea.
玫瑰 is pronounced méigui in casual speech (the second syllable 瑰 is neutral/light here, not guī). Hence 玫瑰果 méiguiguǒ rather than méiguīguǒ, even though 瑰 on its own is guī.