[, ] () a new product that is closely related to existing products and is sold using an existing brand name; the practice of marketing products in this way产品线扩展（与现有产品密切相关并且使用现有品牌名称销售的新产品）◆We are developing two new apple flavours as a line extension of our best-selling classic apple juice.我们正在开发两种新的苹果口味，以扩展我们最畅销的经典浓缩苹果汁的产品线。