term:

Reason

reason n

1 : an underlying ground, justification, purpose, motive, or inducement [required to provide s for the termination in writing]
2 a : the faculty of comprehending, inferring, or distinguishing esp. in a fair and orderly way
b : the proper and sane exercise of the mind

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.