extender

ex.tend.er

n.（名词）
A substance added to another substance to modify, dilute, or adulterate it:
增补剂：被加到另一种物质上的物质，用来变更，稀释或掺杂它：
例句：
meat loaf that contained oatmeal as an extender.
包容燕麦片的肉块用作增补剂