Noun. 1. pistil-the female ovule-bearing part of a flower composed of ovary and style and stigma. blossom, flower, bloom-reproductive organ of angiosperm plants especially one having showy or colorful parts. reproductive structure-the parts of a plant involved in its reproduction.simple pistil-consists of one carpel.. pistil-the female ovule-bearing part of a flower composed of ovary and style and stigma. blossom, flower, bloom-reproductive organ of angiosperm plants especially one having showy or colorful parts.