Short definition
Green, plant-like aromas and flavors in wine such as bell pepper, cut grass, or fresh herbs.
Sauvignon Blanc from the Loire smells like freshly cut grass and gooseberry — that is herbaceous character. Cabernet Franc often shows green bell pepper. In small doses, it adds freshness and complexity. Too much, especially in reds, usually means the grapes were picked before full ripeness. Climate and harvest timing are the main factors.