preservative

详细解释:a. 有助于保存的, 有保存力的
n. 预防药, 防腐剂
【化】 防腐剂; 保存剂
【医】 防腐剂, 保存剂

英语解释：

名词 preservative:

a chemical compound that is added to protect against decay or decomposition

形容词 preservative:

tending or having the power to preserve

例句：

Salt is a common food preservative.盐是一种常用的食物防腐剂。