vegetable为什么是可数名词？

vegetable
[5vedVitEbl]
n.
蔬菜, 植物, 生活呆板单调的人
adj.
蔬菜的, 植物的

vegetable
veg.e.ta.ble
AHD:[vµj“t…-b…l, vµj“¹-t…-]
D.J.[6ved9t*b*l, 6ved9!t*-]
K.K.[6vWd9t*b*l, 6vWd9!t*-]
n.Abbr. veg.（名词）缩写 veg.
A plant cultivated for an edible part, such as the root of the beet, the leaf of spinach, or the flower buds of broccoli or cauliflower.
蔬菜：因其可食部分而种植的植物，如甜菜根、菠菜叶或者椰菜、花椰菜的花蕾等
The edible part of such a plant.
这种蔬菜的可食部分
A member of the vegetable kingdom; a plant.
一种蔬菜：蔬菜王国的一员；植物
A person who is regarded as dull, passive, or unresponsive.
生活呆板、懒散的人：一个愚笨的、木纳的和无反应的人
adj.（形容词）
Of, relating to, or derived from plants or a plant.
植物的：属于、关于或源于植物的
Suggestive of or resembling a plant.
似植物的：使人联想或象植物的
Growing or multiplying like plants.
繁衍的，广泛生长的：象植物那样生长或繁殖的

From Middle English [living and growing as plants do]
源自 中古英语 [象植物那样生活和生长的]
from