supplementary

additional, extra, supplementary

这些形容词均有“另加的，额外的”之意。
additional: 由名词additon派生出的形容词，指在原有基础上添加上去的。
extra: 指不包括本身而额外加上去的部分。
supplementary: 由名词supplement派生而来，指对原有的追加或补究。

形容词 supplementary:

1. functioning in a subsidiary or supporting capacity
   同义词：auxiliary, subsidiary, supplemental
2. added to complete or make up a deficiency
   同义词：supplemental

1. A book or bound collection of maps, sometimes with supplementary illustrations and graphic analyses.
   地图册，图表集将地图装订而成的书册，有时附有增补说明或图表分析
2. Journalism in which a news story is presented primarily through photographs with supplementary written copy.
   摄影新闻(工作), 摄影图片报道主要通过照片和附加书面注释来报导新闻的报刊杂志
3. A supplementary set of keys, usually numerical and arranged like a calculator, added to a keyboard.
   一组增设的键盘，通常是数字型的，其排列方式与计算器的排列方式相似，附设在主键盘上。
4. A supplementary grant may be awarded at the discretion of the committee.
   委员会可能酌情追加一笔补助金。