As defined in the Honor manual, plagiarism is "the act of using someone else's words or ideas as your own without giving proper credit to the source." Here are some resources to aid in the writing process as well as to help with citing your sources.

The Citadel's Writing Center resources page includes different topics from "The Writer's Toolbox" and links to other useful writing-related websites.
http://citadel.edu/wlcenter/

The Merriam-Webster online dictionary and thesaurus (the URL may be shortened to "m-w.com").
http://www.m-w.com/dictionary.htm

APA's online guide to writing style.
http://www.apastyle.org/

MLA's online guide to writing style.
http://www.mla.org/

Bartleby.com offers a basic writing guide, a description of elements of writing style, and a discussion of various writing-related issues.
http://www.bartleby.com

Bedford/St. Martin's offers a quick guide to online sources and citations.
http://www.bedfordstmartins.com/online/index.html

Roget's online thesaurus.
http://humanities.uchicago.edu/orgs/ARTFL/forms_unrest/ROGET.html