Here are some examples of how "intro" is used in English words:
* Introspection: The process of looking inward at one's own thoughts and feelings.
* Introduce: To bring something or someone into a place or situation.
* Introvert: A person who tends to focus on their own thoughts and feelings rather than on external things.
* Introduction: The beginning part of something, such as a book or speech.
Therefore, the definition of the root word "intro" is "within," "inward," "beginning," or "starting."