From the Rice Honor System Handbook: Academic Fraud and the Honor System:
"Academic fraud is one of the areas of university life that fall within the scope of the Honor System. Violating the Honor Code requirements of an assignment or failing to credit one's sources constitutes academic fraud and would, therefore, violate the Honor Code."
You know you are plagiarizing if you don't cite your source when you:
The Center for Academic Integrity (CAI) defines academic integrity as "a commitment, even in the face of adversity, to five fundamental values: honesty, trust, fairness, respect, and responsibility". (Fundamental Values of Academic Integrity)
Integral to these values is the importance of giving authors and artists credit when you make use of their work in your papers and projects.
plagiarize /pláyjrz/ v.tr. (also absol.)
1. take and use (the thoughts, writings, inventions, etc., of another person) as one’s own.
2. pass off the thoughts, etc., of (another person) as one’s own.
--The Oxford American Dictionary of Current English. Oxford University Press, 1999. Oxford Reference Online. Oxford University Press. Rice University. 5 February 2010 <http://www.oxfordreference.com.ezproxy.rice.edu/views/ENTRY.html?subview=Main&entry=t21.e23247>