Wiktionary
n. A format of analog television signal that is split into multiple components, typically each carrying a different colour
Wikipedia
Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Component video can be contrasted with composite video ( NTSC, PAL or SECAM) in which all the video information is combined into a single line-level signal that is used in analog television. Like composite, component-video cables do not carry audio and are often paired with audio cables.
When used without any other qualifications the term component video usually refers to analog component video with sync on luma.