is the word "Shadow" a noun/verb/adverb/ or adjective?
Shadow can be used as three of the four parts of speech you've named. See the definitions of this word.
http://dictionary.reference.com/browse/shadow
The word "Shadow" can be used as both a noun and a verb. It is important to understand the context in which it is being used to determine its part of speech. To figure this out, you can consider the definition and usage of the word.
As a noun, "Shadow" typically refers to a dark area that is created when an object blocks a source of light. For example, "The tree cast a long shadow on the ground." Here, "shadow" is used as a noun.
As a verb, "Shadow" means to follow or accompany someone closely, especially without them noticing. For instance, "The detective shadowed the suspect to gather evidence." In this case, "shadow" functions as a verb.
It is important to note that "Shadow" can also be used metaphorically or in other specialized contexts, but the above examples cover the most common usages as a noun and a verb.