component 指一个整体的组成部分。
constituent 常可与component换用，指某一整体不可少的部分或成分。
element 指一个整体必不可少或固有的部分，强调一个复杂整体中最基本、最简单的元件、元素或成分等。
ingredient 普通用词，含义笼统。既可指混在一起而本身没有变化的物质，如配料，又可指与别的物质混在一起，发生了变化的成分。
参考例句
1. Reject - reports the receipt and rejection of an incorrect component. 拒绝--报告接受或拒绝一个不正确的组件。
2. Programme of major component repair or replacement during the project life. 在项目生命期内，主要部件修复或置换的计划；
3. The goal was to provide more precise synchronization and relative timing of the three component video signals. 目标是提供更为精确的同步信息及相关的三个分量视频信号的时序。
英英解释
n.
1. an abstract part of something
2. something determined in relation to something that includes it
3. an artifact that is one of the individual parts of which a composite entity is made up; especially a
